microblaze: Use CFLAGS_KERNEL instead of CFLAGS

Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/Makefile

@@ -32,15 +32,13 @@ CPUFLAGS-1 += $(call cc-option,-mcpu=v$(CPU_VER))
 
 # The various CONFIG_XILINX cpu features options are integers 0/1/2...
 # rather than bools y/n
-CFLAGS += $(CPUFLAGS-1)
-CFLAGS += $(CPUFLAGS-2)
 
 # r31 holds current when in kernel mode
-CFLAGS += -ffixed-r31
+CFLAGS_KERNEL += -ffixed-r31 $(CPUFLAGS-1) $(CPUFLAGS-2)
 
 LDFLAGS_BLOB := --format binary --oformat elf32-microblaze
 
-LIBGCC := $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
+LIBGCC := $(shell $(CC) $(CFLAGS_KERNEL) -print-libgcc-file-name)
 
 head-y		:= arch/microblaze/kernel/head.o
 libs-y		+= arch/microblaze/lib/ $(LIBGCC)