MIPS: BMIPS: Introduce bmips.h

bmips.h contains BMIPS definitions that are useful for SMP, vector
relocation, performance counters, etc.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2973/


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