am33xx: Rework pinmux functions

- Move definition of the EEPROM contents to <asm/arch/sys_proto.h>
  - Make some defines a little less generic now.
- Pinmux must be done by done by SPL now.
- Create 3 pinmux functions, uart0, i2c0 and board.
- Add pinmux specific to Starter Kit EVM for MMC now.

Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/board/ti/am335x/Makefile b/board/ti/am335x/Makefile
index e3609bc..ca50eef 100644
--- a/board/ti/am335x/Makefile
+++ b/board/ti/am335x/Makefile
@@ -18,7 +18,9 @@
 
 LIB	= $(obj)lib$(BOARD).o
 
+ifdef CONFIG_SPL_BUILD
 COBJS	:= mux.o
+endif
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))