mfd: Add 8420 variant to db8500-prcmu

Signed-off-by: Bengt Jonsson <bengt.g.jonsson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c
index 06a3c32..ebc1e86 100644
--- a/drivers/mfd/db8500-prcmu.c
+++ b/drivers/mfd/db8500-prcmu.c
@@ -2636,6 +2636,8 @@
 		return "U9500 C2";
 	case PRCMU_FW_PROJECT_U8520:
 		return "U8520";
+	case PRCMU_FW_PROJECT_U8420:
+		return "U8420";
 	default:
 		return "Unknown";
 	}