[MIPS] Enable -ffunction-sections sections.

-ffunction-sections serves as a workaround for the problems caused by the
limited branch range in some inline assembler fragments for very large
compilation units.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -14,7 +14,7 @@
 
 KBUILD_DEFCONFIG := ip22_defconfig
 
-cflags-y :=
+cflags-y := -ffunction-sections
 
 #
 # Select the object file format to substitute into the linker script.