powerpc/64s: Merge HV and non-HV paths for doorbell IRQ replay

This results in smaller code, and fewer branches. This relies on the
fact that both the 0xe80 and 0xa00 handlers call the same upper level
code, namely doorbell_exception().
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Mention we rely on the implementation of the 0xe80/0xa00 handlers]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/entry_64.S

@@ -966,11 +966,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 #ifdef CONFIG_PPC_BOOK3E
 	cmpwi	cr0,r3,0x280
 #else
-	BEGIN_FTR_SECTION
-		cmpwi	cr0,r3,0xe80
-	FTR_SECTION_ELSE
-		cmpwi	cr0,r3,0xa00
-	ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
+	cmpwi	cr0,r3,0xa00
 #endif /* CONFIG_PPC_BOOK3E */
 	bne	1f
 	addi	r3,r1,STACK_FRAME_OVERHEAD;

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

@@ -1676,7 +1676,7 @@ _GLOBAL(__replay_interrupt)
 	cmpwi	r3,0x500
 	beq	hardware_interrupt_common
 BEGIN_FTR_SECTION
-	cmpwi	r3,0xe80
+	cmpwi	r3,0xa00
 	beq	h_doorbell_common_msgclr
 	cmpwi	r3,0xea0
 	beq	h_virt_irq_common

arch/powerpc/kernel/irq.c

@@ -207,8 +207,6 @@ notrace unsigned int __check_irq_replay(void)
 #else
 	if (happened & PACA_IRQ_DBELL) {
 		local_paca->irq_happened &= ~PACA_IRQ_DBELL;
-		if (cpu_has_feature(CPU_FTR_HVMODE))
-			return 0xe80;
 		return 0xa00;
 	}
 #endif /* CONFIG_PPC_BOOK3E */