fix: Make variable usage consistent in Makefile

Signed-off-by: Jack Chen <[email protected]>

Makefile

@@ -14,9 +14,9 @@ INCLUDE_DELAYED_START_BUILD_CORE:="false"
 INCLUDE_DELAYED_START_BUILD_SUPPORT:="true"
 
 # change the following boolean flag to enable or disable the Full RELRO (RELocation Read Only) for linux ELF (Executable and Linkable Format) binaries
-ENABLE_FULL_RELRO:="true"
+ENABLE_FULL_RELRO=true
 # change the following boolean flag to enable or disable PIE for linux binaries which is needed for ASLR (Address Space Layout Randomization) on Linux, the ASLR support on Windows is enabled by default
-ENABLE_PIE:="true"
+ENABLE_PIE=true
 
 GO=go
 
@@ -67,7 +67,7 @@ endif
 GOFLAGS=-ldflags "-s -w -X github.com/edgexfoundry/edgex-go.Version=$(VERSION) $(ENABLE_FULL_RELRO_GOFLAGS)" -trimpath -mod=readonly
 GOTESTFLAGS?=-race
 
-ifeq ($(ENABLE_PIE), "true")
+ifeq ($(ENABLE_PIE), true)
 	GOFLAGS += -buildmode=pie
 endif