arm: freescale: Rename initdram() to fsl_initdram()

This function name shadows a global name but is in fact different. This
is very confusing. Rename it to help with the following refactoring.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/ls2080a/ddr.c b/board/freescale/ls2080a/ddr.c
index d340c41..9d176d3 100644
--- a/board/freescale/ls2080a/ddr.c
+++ b/board/freescale/ls2080a/ddr.c
@@ -158,7 +158,8 @@
 	return 0;
 }
 #endif
-int initdram(void)
+
+int fsl_initdram(void)
 {
 	puts("Initializing DDR....");