arm: rmobile: lager: Add CONFIG_SCIF_USE_EXT_CLK

SCIF of lager use external clock mode.
This enables external clock mode on lager board.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
diff --git a/include/configs/lager.h b/include/configs/lager.h
index 6bd1ce8..699135f 100644
--- a/include/configs/lager.h
+++ b/include/configs/lager.h
@@ -90,6 +90,7 @@
 /* SCIF */
 #define CONFIG_SCIF_CONSOLE
 #define CONFIG_CONS_SCIF0
+#define CONFIG_SCIF_USE_EXT_CLK
 #undef	CONFIG_SYS_CONSOLE_INFO_QUIET
 #undef	CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
 #undef	CONFIG_SYS_CONSOLE_ENV_OVERWRITE