powerpc: Clear MSR_RI during RTAS calls

RTAS should never cause an exception but if it does (for example accessing
outside our RMO) then we might go a long way through the kernel before
oopsing. If we unset MSR_RI we should at least stop things on exception
exit.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/entry_64.S

@@ -791,9 +791,8 @@ _GLOBAL(enter_rtas)
 
         li      r9,1
         rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
-	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP
+	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI
 	andc	r6,r0,r9
-	ori	r6,r6,MSR_RI
 	sync				/* disable interrupts so SRR0/1 */
 	mtmsrd	r0			/* don't get trashed */