MIPS: smp-cps: use CPC core-other locking

The core which the CPC core-other region relates to is based upon the
core-local core-other addressing register. As its name suggests this
register is shared between all VPEs within a core, and if there is a
possibility that multiple VPEs within a core will attempt to access
another core simultaneously then locking is required. This wasn't
previously a problem with the only user being cpu0 during boot, but will
be an issue once hotplug is implemented & may race with other users such
as cpuidle.

Signed-off-by: Paul Burton <[e-mail]>

arch/mips/kernel/smp-cps.c

···
 	write_gcr_access(access);
 
 	if (mips_cpc_present()) {
-		/* Select the appropriate core */
-		write_cpc_cl_other(core << CPC_Cx_OTHER_CORENUM_SHF);
-
 		/* Reset the core */
+		mips_cpc_lock_other(core);
 		write_cpc_co_cmd(CPC_Cx_CMD_RESET);
+		mips_cpc_unlock_other();
 	} else {
 		/* Take the core out of reset */
 		write_gcr_co_reset_release(0);