libsel4bench: add support for ARM Cortex-A55

[axel-h]

Another fix for seL4/sel4bench#32

This fixed the error

  [182/299] Building C object apps/sel4bench/seL4_libs/libsel4bench/CMakeFiles/sel4bench.dir/src/arch/arm/armv/armv8-a/event_counters.c.obj
  FAILED: apps/sel4bench/seL4_libs/libsel4bench/CMakeFiles/sel4bench.dir/src/arch/arm/armv/armv8-a/event_counters.c.obj
  /usr/bin/ccache /usr/bin/aarch64-linux-gnu-gcc --sysroot=/github/workspace/build  -I/github/workspace/projects/seL4_libs/libsel4bench/include -I/github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm/armv/armv8-a -I/github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm/cpu/cortex-a55 -I/github/workspace/projects/seL4_libs/libsel4bench/sel4_arch_include/aarch64 -I/github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm -I/github/workspace/projects/seL4_libs/libsel4bench/src -Iapps/sel4bench/musllibc/build-temp/stage/include -I/github/workspace/kernel/libsel4/include -I/github/workspace/kernel/libsel4/arch_include/arm -I/github/workspace/kernel/libsel4/sel4_arch_include/aarch64 -I/github/workspace/kernel/libsel4/sel4_plat_include/quartz64 -I/github/workspace/kernel/libsel4/mode_include/64 -Ilibsel4/include -Ilibsel4/arch_include/arm -Ilibsel4/sel4_arch_include/aarch64 -I/github/workspace/projects/util_libs/libutils/include -I/github/workspace/projects/util_libs/libutils/arch_include/arm -Iapps/sel4bench/util_libs/libutils/gen_config -Ilibsel4/autoconf -Ikernel/gen_config -Ilibsel4/gen_config -march=armv8-a  -D__KERNEL_64__ -O3 -DNDEBUG -ffunction-sections -fdata-sections -nostdinc -fno-pic -fno-pie -fno-stack-protector -fno-asynchronous-unwind-tables -ftls-model=local-exec -mstrict-align -mno-outline-atomics -std=gnu11 -MD -MT apps/sel4bench/seL4_libs/libsel4bench/CMakeFiles/sel4bench.dir/src/arch/arm/armv/armv8-a/event_counters.c.obj -MF apps/sel4bench/seL4_libs/libsel4bench/CMakeFiles/sel4bench.dir/src/arch/arm/armv/armv8-a/event_counters.c.obj.d -o apps/sel4bench/seL4_libs/libsel4bench/CMakeFiles/sel4bench.dir/src/arch/arm/armv/armv8-a/event_counters.c.obj -c /github/workspace/projects/seL4_libs/libsel4bench/src/arch/arm/armv/armv8-a/event_counters.c
  In file included from /github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm/armv/armv8-a/sel4bench/armv/private.h:9,
                   from /github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm/armv/armv8-a/sel4bench/armv/sel4bench.h:10,
                   from /github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm/sel4bench/arch/sel4bench.h:12,
                   from /github/workspace/projects/seL4_libs/libsel4bench/include/sel4bench/sel4bench.h:13,
                   from /github/workspace/projects/seL4_libs/libsel4bench/src/arch/arm/armv/armv8-a/../../event_counters.h:8,
                   from /github/workspace/projects/seL4_libs/libsel4bench/src/arch/arm/armv/armv8-a/event_counters.c:9:
  /github/workspace/projects/seL4_libs/libsel4bench/arch_include/arm/armv/armv8-a/sel4bench/armv/events.h:74:10: fatal error: sel4bench/cpu/events.h: No such file or directory
     74 | #include <sel4bench/cpu/events.h>
        |          ^~~~~~~~~~~~~~~~~~~~~~~~
  compilation terminated.