ARM: pull in <asm/simd.h> from asm-generic

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

idea is taken here - https://github.com/savoca/furnace_kernel_lge_mako/commit/d7d44e37e4f1b6207d54091b3eda9575e75f00de