spl/nand: introduce CONFIG_SPL_NAND_DRIVERS, _BASE, and _ECC.

Some small SPLs do not use nand_base.c, and a subset of those also
require a special driver.  Some SPLs need software ECC but others can't
fit it.

All existing boards that specify CONFIG_SPL_NAND_SUPPORT have these
symbols added to preserve existing behavior.

Signed-off-by: Scott Wood <scottwood@freescale.com>
--
v2: use positive logic for including bits of NAND, rather than
a MINIMAL symbol that excludes things.
diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index beb99ca..d8a2dfc 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -26,21 +26,33 @@
 LIB	:= $(obj)libnand.o
 
 ifdef CONFIG_CMD_NAND
+
 ifdef CONFIG_SPL_BUILD
-ifdef CONFIG_SPL_NAND_SIMPLE
-COBJS-y += nand_spl_simple.o
+
+ifdef CONFIG_SPL_NAND_DRIVERS
+NORMAL_DRIVERS=y
 endif
-ifdef CONFIG_SPL_NAND_LOAD
-COBJS-y	+= nand_spl_load.o
-endif
-else
+
+COBJS-$(CONFIG_SPL_NAND_SIMPLE) += nand_spl_simple.o
+COBJS-$(CONFIG_SPL_NAND_LOAD) += nand_spl_load.o
+COBJS-$(CONFIG_SPL_NAND_ECC) += nand_ecc.o
+COBJS-$(CONFIG_SPL_NAND_BASE) += nand_base.o
+
+else # not spl
+
+NORMAL_DRIVERS=y
+
 COBJS-y += nand.o
 COBJS-y += nand_bbt.o
 COBJS-y += nand_ids.o
 COBJS-y += nand_util.o
-endif
 COBJS-y += nand_ecc.o
 COBJS-y += nand_base.o
+
+endif # not spl
+
+ifdef NORMAL_DRIVERS
+
 COBJS-$(CONFIG_NAND_ECC_BCH) += nand_bch.o
 
 COBJS-$(CONFIG_NAND_ATMEL) += atmel_nand.o
@@ -65,7 +77,9 @@
 COBJS-$(CONFIG_TEGRA_NAND) += tegra_nand.o
 COBJS-$(CONFIG_NAND_OMAP_GPMC) += omap_gpmc.o
 COBJS-$(CONFIG_NAND_PLAT) += nand_plat.o
-endif
+
+endif # drivers
+endif # nand
 
 COBJS	:= $(COBJS-y)
 SRCS	:= $(COBJS:.o=.c)