MIPS: Correct the comment for and reformat `movf_func'

Correct a copy-and-paste issue with the description for `movf_func'
referring to `movt_func'.  Reformat the former function to match the
latter.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9675/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>