fix build errors using gcc-4.7

Error: selected processor does not support ARM mode `smc #0'
error: DIV usage mismatch between arch/arm/boot/compressed/head.o and output
error: DIV usage mismatch between arch/arm/boot/compressed/misc.o and output
error: DIV usage mismatch between arch/arm/boot/compressed/decompress.o and output
error: DIV usage mismatch between arch/arm/boot/compressed/lib1funcs.o and output
error: DIV usage mismatch between arch/arm/boot/compressed/ashldi3.o and output

Change-Id: I1251b843bb9b4c74ba8039fd194e3aed2183cf5b