This patch adds the Vector Multiply Unsigned Word Modulo (vmuluwm)
instruction.

The existing VARITH_DO macro is re-used to (trivially) instantiate
the helper code.

Since bits 21-31 of any vmuluwm instruction is 137, the instruction
is coded as a dual to vmulouw (bits 21-31 = 136).
Signed-off-by: NTom Musta <tommusta@gmail.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>