rcar_gen3: plat: Zero-terminate the string in unsigned_num_print()

Make sure the string generated in unsigned_num_print() is zero-terminated.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Change-Id: Ic0ac1ebca255002522159a9152ab41991f043d05
diff --git a/plat/renesas/rcar/bl2_plat_setup.c b/plat/renesas/rcar/bl2_plat_setup.c
index 8910967..add2a4f 100644
--- a/plat/renesas/rcar/bl2_plat_setup.c
+++ b/plat/renesas/rcar/bl2_plat_setup.c
@@ -134,6 +134,7 @@
 
 	while (--i >= 0)
 		*string++ = num_buf[i];
+	*string = 0;
 }
 
 #if (RCAR_LOSSY_ENABLE == 1)