powerpc/64s: Add msgp facility unavailable log string

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Author: npiggin

arch/powerpc/kernel/traps.c

@@ -1440,6 +1440,7 @@ void facility_unavailable_exception(struct pt_regs *regs)
 		[FSCR_TM_LG] = "TM",
 		[FSCR_EBB_LG] = "EBB",
 		[FSCR_TAR_LG] = "TAR",
+		[FSCR_MSGP_LG] = "MSGP",
 	};
 	char *facility = "unknown";
 	u64 value;