powerpc: Enforce usage of RA 0-R31 where possible

Some macros use RA where when RA=R0 the values is 0, so make this
the enforced mnemonic in the macro.

Idea suggested by Andreas Schwab.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index bc36734..ecba705 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -903,7 +903,7 @@
 	bne	1b				/* If not, repeat */
 
 	/* Invalidate all TLBs */
-	PPC_TLBILX_ALL(R0,R0)
+	PPC_TLBILX_ALL(0,R0)
 	sync
 	isync
 
@@ -961,7 +961,7 @@
 	tlbwe
 
 	/* Invalidate TLB1 */
-	PPC_TLBILX_ALL(R0,R0)
+	PPC_TLBILX_ALL(0,R0)
 	sync
 	isync
 
@@ -1020,7 +1020,7 @@
 	tlbwe
 
 	/* Invalidate TLB1 */
-	PPC_TLBILX_ALL(R0,R0)
+	PPC_TLBILX_ALL(0,R0)
 	sync
 	isync
 
@@ -1138,7 +1138,7 @@
 	tlbwe
 #endif /* CONFIG_PPC_EARLY_DEBUG_WSP */
 
-	PPC_TLBILX(0,R0,R0)
+	PPC_TLBILX(0,0,R0)
 	sync
 	isync