powerpc/64s: Move SET_SCRATCH0() into EXCEPTION_PROLOG_PSERIES()

EXCEPTION_PROLOG_PSERIES() only has two users, STD_EXCEPTION_PSERIES()
and STD_EXCEPTION_HV() both of which "call" SET_SCRATCH0(), so just
move SET_SCRATCH0() into EXCEPTION_PROLOG_PSERIES().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/exception-64s.h

@@ -344,6 +344,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 	__EXCEPTION_PROLOG_PSERIES_1_NORI(label, h)
 
 #define EXCEPTION_PROLOG_PSERIES(area, label, h, extra, vec)		\
+	SET_SCRATCH0(r13);		/* save r13 */			\
 	EXCEPTION_PROLOG_0(area);					\
 	EXCEPTION_PROLOG_1(area, extra, vec);				\
 	EXCEPTION_PROLOG_PSERIES_1(label, h);
@@ -552,7 +553,6 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
  * Exception vectors.
  */
 #define STD_EXCEPTION_PSERIES(vec, label)			\
-	SET_SCRATCH0(r13);		/* save r13 */		\
 	EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label,		\
 				 EXC_STD, KVMTEST_PR, vec);	\
 
@@ -567,7 +567,6 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 	EXCEPTION_PROLOG_PSERIES_1(label, EXC_STD)
 
 #define STD_EXCEPTION_HV(loc, vec, label)			\
-	SET_SCRATCH0(r13);	/* save r13 */			\
 	EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label,		\
 				 EXC_HV, KVMTEST_HV, vec);