powerpc/64s: Avoid a branch for ppc_msgsnd

IPIs are a pretty hot path and we already have the ability to do asm feature
patching, so use it.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Change log detail]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/dbell.h

@@ -38,10 +38,8 @@ enum ppc_dbell {
 
 static inline void _ppc_msgsnd(u32 msg)
 {
-	if (cpu_has_feature(CPU_FTR_HVMODE))
-		__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
-	else
-		__asm__ __volatile__ (PPC_MSGSNDP(%0) : : "r" (msg));
+	__asm__ __volatile__ (ASM_FTR_IFSET(PPC_MSGSND(%1), PPC_MSGSNDP(%1), %0)
+				: : "i" (CPU_FTR_HVMODE), "r" (msg));
 }
 
 /* sync before sending message */