MIPS: Optimize TLB refill for RI/XI configurations.

We don't have to do a separate shift to eliminate the software bits,
just rotate them into the fill and they will be ignored.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4294/


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