stm32mp1: support of STM32MP15x Rev.Z

Add a new revision of STM32MP15x CPU (Rev.Z).

Change-Id: I227dd6d9b3fcc43270015cfb21f60aeb0a8ab658
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Yann Gautier <yann.gautier@st.com>
diff --git a/plat/st/stm32mp1/stm32mp1_private.c b/plat/st/stm32mp1/stm32mp1_private.c
index fd60db2..499766d 100644
--- a/plat/st/stm32mp1/stm32mp1_private.c
+++ b/plat/st/stm32mp1/stm32mp1_private.c
@@ -261,6 +261,9 @@
 	case STM32MP1_REV_B:
 		cpu_r = "B";
 		break;
+	case STM32MP1_REV_Z:
+		cpu_r = "Z";
+		break;
 	default:
 		cpu_r = "?";
 		break;