ARM: rmobile: Introduce weak default board_init()

Introduce weak default board_init() in rcar-common/common.c , which
allows complete removal of ebisu.c and condor.c at the same time .

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/board/renesas/rcar-common/common.c b/board/renesas/rcar-common/common.c
index 17940aa..3a0e88b 100644
--- a/board/renesas/rcar-common/common.c
+++ b/board/renesas/rcar-common/common.c
@@ -49,6 +49,11 @@
 	return 0;
 }
 
+int __weak board_init(void)
+{
+	return 0;
+}
+
 #if defined(CONFIG_RCAR_GEN3)
 #define RST_BASE	0xE6160000
 #define RST_CA57RESCNT	(RST_BASE + 0x40)