AArch64: Improve JIT code for spin lock

[knn-k]

AArch64 JIT generates instruction sequence of releasing VM access using dmb, ldxr, and stxr.

openj9/runtime/compiler/aarch64/codegen/ARM64JNILinkage.cpp

Line 72 in 4114e7b

void J9::ARM64::JNILinkage::releaseVMAccess(TR::Node *callNode, TR::Register *vmThreadReg, TR::Register *scratchReg0, TR::Register *scratchReg1, TR::Register *scratchReg2, TR::Register *scratchReg3)

The instruction sequence may be improved by using Load-Acquire instructions, as discussed in #20188 (comment)