rockchip: elgin-rv1108: use board_early_init_f for per-boar init

Use board_early_init_f() for per-board init operation and
use board_init() from common board file.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/board/elgin/elgin_rv1108/elgin_rv1108.c b/board/elgin/elgin_rv1108/elgin_rv1108.c
index 0de1f42..70a1245 100644
--- a/board/elgin/elgin_rv1108/elgin_rv1108.c
+++ b/board/elgin/elgin_rv1108/elgin_rv1108.c
@@ -50,11 +50,16 @@
 
 #define MODEM_ENABLE_GPIO 111
 
-int board_init(void)
+int board_early_init_f(void)
 {
 	gpio_request(MODEM_ENABLE_GPIO, "modem_enable");
 	gpio_direction_output(MODEM_ENABLE_GPIO, 0);
 
+	return 0;
+}
+
+int board_init(void)
+{
 	return 0;
 }