MIPS: CM: WARN on attempt to lock invalid VP, not BUG

Rather than using BUG_ON in the case of an invalid attempt to lock
access to a non-zero VP on a pre-CM3 system, use WARN_ON so that we have
even the slightest chance of recovery.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16194/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/mips-cm.c

@@ -282,7 +282,7 @@ void mips_cm_lock_other(unsigned int core, unsigned int vp)
 		spin_lock_irqsave(this_cpu_ptr(&cm_core_lock),
 				  *this_cpu_ptr(&cm_core_lock_flags));
 	} else {
-		BUG_ON(vp != 0);
+		WARN_ON(vp != 0);
 
 		/*
 		 * We only have a GCR_CL_OTHER per core in systems with