arm: lib: import muldi3.S from Linux

arm: lib: import muldi3.S from Linux

Import muldi3.S from Linux 4.4.6 , commit 0d1912303e54ed1b2a371be0bba51c384dd57326
on arm32. This file implements __aeabi_lmul and it's alias __muldi3, which
is needed when doing Thumb1 builds.

This patch also defines CONFIG_THUMB2_KERNEL and CONFIG_ARM_ASM_UNIFIED
which is necessary for correct build of these files both in ARM and
Thumb mode, just like Linux does.

Signed-off-by: Marek Vasut <[email protected]>
Cc: Albert Aribaud <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Tom Rini <[email protected]>
Reviewed-by: Tom Rini <[email protected]>