renesas-ra: Add a macro definition to avoid compile error of FSP v4.4.0.

FSP v4.4.0 refers to CMSIS V5.4.1, and __COMPILER_BARRIER() is used in bsp.
On the other hand, lib/cmsis is V5.1.0 and the macro is not defined.
Therefore, compile error happens.
As the workaround, the macro definition is added.
If lib/cmsis is updated in the future, this addition can be removed.

Signed-off-by: Takeo Takahashi <takeo.takahashi.xv@renesas.com>

ports/renesas-ra/Makefile

@@ -89,6 +89,7 @@ SYSTEM_FILE ?= lib/fsp/ra/fsp/src/bsp/cmsis/Device/RENESAS/Source/system.o
 # Select the cross compile prefix
 CROSS_COMPILE ?= arm-none-eabi-
 
+INC += -imacros boards/compiler_barrier.h
 INC += -I.
 INC += -I$(TOP)
 INC += -I$(BUILD)

ports/renesas-ra/boards/compiler_barrier.h

@@ -0,0 +1,4 @@
+// we need to provide a definition of __COMPILER_BARRIER() defined in cmsis/cmsis_gcc.h V5.4.1 for FSP v4.4.0
+#ifndef   __COMPILER_BARRIER
+  #define __COMPILER_BARRIER()                   __ASM volatile ("" ::: "memory")
+#endif