MIPS: Set compiler options only after the compiler prefix has ben set.

Otherwise indigestable options might be passed to the host compiler.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -14,8 +14,6 @@
 
 KBUILD_DEFCONFIG := ip22_defconfig
 
-cflags-y := -ffunction-sections
-
 #
 # Select the object file format to substitute into the linker script.
 #
@@ -50,6 +48,8 @@ ifneq ($(SUBARCH),$(ARCH))
   endif
 endif
 
+cflags-y := -ffunction-sections
+
 ifdef CONFIG_32BIT
 ld-emul			= $(32bit-emul)
 vmlinux-32		= vmlinux