MIPS: CM: Add support for reporting CM cache errors

The CM cache error reporting code is not Malta specific and as such it
should live in the mips-cm.c file. Moreover, CM2 and CM3 differ in the
way cache errors are being recorded to the registers so extend the
previous code to add support for the CM3 as well.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10646/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>