board_f: Drop return value from initdram()

At present we cannot use this function as an init sequence call without a
wrapper, since it returns the RAM size. Adjust it to set the RAM size in
global_data instead, and return 0 on success.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/board/freescale/m54418twr/m54418twr.c b/board/freescale/m54418twr/m54418twr.c
index c3bee18..3f1100c 100644
--- a/board/freescale/m54418twr/m54418twr.c
+++ b/board/freescale/m54418twr/m54418twr.c
@@ -25,7 +25,7 @@
 	return 0;
 };
 
-phys_size_t initdram(void)
+int initdram(void)
 {
 	u32 dramsize;
 
@@ -104,7 +104,9 @@
 
 	udelay(100);
 #endif
-	return dramsize;
+	gd->ram_size = dramsize;
+
+	return 0;
 };
 
 int testdram(void)