MIPS: CM: Introduce core-other locking functions

MIPS: CM: Introduce core-other locking functions

Introduce mips_cm_lock_other & mips_cm_unlock_other, mirroring the
existing CPC equivalents, in order to lock access from the current core
to another via the core-other GCR region. This hasn't been required in
the past but with CM3 the CPC starts using GCR_CL_OTHER rather than
CPC_CL_OTHER and this will be required for safety.

[[email protected]: Fix merge conflict.]

Signed-off-by: Paul Burton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: James Hogan <[email protected]>
Cc: Markos Chandras <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/11207/
Signed-off-by: Ralf Baechle <[email protected]>