MIPS: Define Config1 cache field shifts & sizes

These fields will be used from assembly code in a subsequent commit, and
defining the size & offset of each field makes that use easier.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6355/


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