mx31: add "ARM11P power gating" to get_reset_cause

Add missing reset reason 7 to get_reset_cause().

Signed-off-by: Helmut Raiger <helmut.raiger@hale.at>
diff --git a/arch/arm/cpu/arm1136/mx31/generic.c b/arch/arm/cpu/arm1136/mx31/generic.c
index d60afc9..8873fb7 100644
--- a/arch/arm/cpu/arm1136/mx31/generic.c
+++ b/arch/arm/cpu/arm1136/mx31/generic.c
@@ -210,6 +210,8 @@
 		return "WDOG";
 	case 0x0006:
 		return "JTAG";
+	case 0x0007:
+		return "ARM11P power gating";
 	default:
 		return "unknown reset";
 	}