OMAP3 SPL: Add identify_nand_chip function

A number of boards are populated with a PoP chip for both DDR and NAND
memory.  Other boards may simply use this as an easy way to identify
board revs.  So we provide a function that can be called early to reset
the NAND chip and return the result of NAND_CMD_READID.  All of this
code is put into spl_id_nand.c and controlled via CONFIG_SPL_OMAP3_ID_NAND.

Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/arch/arm/cpu/armv7/omap3/Makefile b/arch/arm/cpu/armv7/omap3/Makefile
index 6ebfd32..ac597be 100644
--- a/arch/arm/cpu/armv7/omap3/Makefile
+++ b/arch/arm/cpu/armv7/omap3/Makefile
@@ -31,6 +31,9 @@
 COBJS	+= clock.o
 COBJS	+= mem.o
 COBJS	+= sys_info.o
+ifdef CONFIG_SPL_BUILD
+COBJS-$(CONFIG_SPL_OMAP3_ID_NAND)	+= spl_id_nand.o
+endif
 
 COBJS-$(CONFIG_DRIVER_TI_EMAC)	+= emac.o
 COBJS-$(CONFIG_EMIF4)	+= emif4.o