MIPS: Fix 'write_msa_##' inline macro.

The 'write_msa_##' macro incorrectly uses the 'cfcmsa'
instruction, which should be the 'ctcmsa' instruction.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Reviewed-by: Paul Burton <Paul.Burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6750/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>