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/ls2080ardb/ddr.c b/board/freescale/ls2080ardb/ddr.c
index 029ea61..7002dfb 100644
--- a/board/freescale/ls2080ardb/ddr.c
+++ b/board/freescale/ls2080ardb/ddr.c
@@ -158,7 +158,7 @@
 	}
 }
 
-int initdram(void)
+int fsl_initdram(void)
 {
 #if defined(CONFIG_SPL) && !defined(CONFIG_SPL_BUILD)
 	gd->ram_size = fsl_ddr_sdram_size();