powerpc/64s/exception: improve 0x500 handler code

After the previous cleanup, it becomes possible to consolidate some
common code outside the runtime alternate patching. Also remove
unused labels.

This results in some code change, but unchanged runtime instruction
sequence.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/exceptions-64s.S

@@ -746,32 +746,24 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
 
 
 EXC_REAL_BEGIN(hardware_interrupt, 0x500, 0x100)
-	.globl hardware_interrupt_hv
-hardware_interrupt_hv:
+	SET_SCRATCH0(r13)	/* save r13 */
+	EXCEPTION_PROLOG_0 PACA_EXGEN
 	BEGIN_FTR_SECTION
-		SET_SCRATCH0(r13)	/* save r13 */
-		EXCEPTION_PROLOG_0 PACA_EXGEN
 		EXCEPTION_PROLOG_1 EXC_HV, PACA_EXGEN, 1, 0x500, IRQS_DISABLED
 		EXCEPTION_PROLOG_2_REAL hardware_interrupt_common, EXC_HV, 1
 	FTR_SECTION_ELSE
-		SET_SCRATCH0(r13)	/* save r13 */
-		EXCEPTION_PROLOG_0 PACA_EXGEN
 		EXCEPTION_PROLOG_1 EXC_STD, PACA_EXGEN, 1, 0x500, IRQS_DISABLED
 		EXCEPTION_PROLOG_2_REAL hardware_interrupt_common, EXC_STD, 1
 	ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
 EXC_REAL_END(hardware_interrupt, 0x500, 0x100)
 
 EXC_VIRT_BEGIN(hardware_interrupt, 0x4500, 0x100)
-	.globl hardware_interrupt_relon_hv
-hardware_interrupt_relon_hv:
+	SET_SCRATCH0(r13)	/* save r13 */
+	EXCEPTION_PROLOG_0 PACA_EXGEN
 	BEGIN_FTR_SECTION
-		SET_SCRATCH0(r13)	/* save r13 */
-		EXCEPTION_PROLOG_0 PACA_EXGEN
 		EXCEPTION_PROLOG_1 EXC_HV, PACA_EXGEN, 1, 0x500, IRQS_DISABLED
 		EXCEPTION_PROLOG_2_VIRT hardware_interrupt_common, EXC_HV
 	FTR_SECTION_ELSE
-		SET_SCRATCH0(r13)	/* save r13 */
-		EXCEPTION_PROLOG_0 PACA_EXGEN
 		EXCEPTION_PROLOG_1 EXC_STD, PACA_EXGEN, 1, 0x500, IRQS_DISABLED
 		EXCEPTION_PROLOG_2_VIRT hardware_interrupt_common, EXC_STD
 	ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)