MIPS: traps: Dump the PageGrain and Wired registers on MC

They can be useful to determine how the MMU is configured on a MC
exception.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8401/


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