When the toolchain doesn't support MSA we encode MSA instructions
explicitly in assembly. Unfortunately we use .word for both MIPS and
microMIPS encodings which is wrong, since 32-bit microMIPS instructions
are made up from a pair of halfwords.

- The most significant halfword always comes first, so for little endian
  builds the halves will be emitted in the wrong order.

- 32-bit alignment isn't guaranteed, so the assembler may insert a
  16-bit nop instruction to pad the instruction stream to a 32-bit
  boundary.

Use the new instruction encoding macros to encode microMIPS MSA
instructions correctly.

Fixes: d96cc3d1 ("MIPS: Add microMIPS MSA support.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <Paul.Burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13312/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>