omap-common: reorganize spl.c

split-up spl.c into spl.c, spl_mmc.c and spl_nand.c. This avoids problems
with missing defines if a board does not use mmc or nand. This includes
adding spl_ prefix to some functions which are now public. spl_image_t is now
a public type. Added some of the common functions to omap-common.h

Signed-off-by: Simon Schwarz <simonschwarzcor@gmail.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>
diff --git a/arch/arm/cpu/armv7/omap-common/Makefile b/arch/arm/cpu/armv7/omap-common/Makefile
index ea9f8ec..0b96b47 100644
--- a/arch/arm/cpu/armv7/omap-common/Makefile
+++ b/arch/arm/cpu/armv7/omap-common/Makefile
@@ -33,6 +33,12 @@
 
 ifdef CONFIG_SPL_BUILD
 COBJS	+= spl.o
+ifdef CONFIG_SPL_NAND_SUPPORT
+COBJS	+= spl_nand.o
+endif
+ifdef CONFIG_SPL_MMC_SUPPORT
+COBJS	+= spl_mmc.o
+endif
 endif
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)