Convert CONFIG_NAND_OMAP_GPMC et al and CONFIG_NAND_MXC to Kconfig

This converts the following to Kconfig:
   CONFIG_NAND_MXC
   CONFIG_NAND_OMAP_GPMC
   CONFIG_NAND_OMAP_GPMC_PREFETCH
   CONFIG_NAND_OMAP_ELM
   CONFIG_SPL_NAND_AM33XX_BCH
   CONFIG_SPL_NAND_SIMPLE
   CONFIG_SYS_NAND_BUSWIDTH_16BIT

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
[trini: Finish migration of CONFIG_SPL_NAND_SIMPLE, fix some build issues,
        add CONFIG_NAND_MXC so we can do CONFIG_SYS_NAND_BUSWIDTH_16BIT]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index 7efef6b..abd1aa7 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -11,6 +11,7 @@
 	select ARM_ERRATA_621766
 	select ARM_ERRATA_725233
 	select USE_TINY_PRINTF
+	imply NAND_OMAP_GPMC
 	imply SPL_EXT_SUPPORT
 	imply SPL_FAT_SUPPORT
 	imply SPL_GPIO_SUPPORT
@@ -30,6 +31,8 @@
 config OMAP44XX
 	bool "OMAP44XX SoC"
 	select USE_TINY_PRINTF
+	imply NAND_OMAP_ELM
+	imply NAND_OMAP_GPMC
 	imply SPL_DISPLAY_PRINT
 	imply SPL_EXT_SUPPORT
 	imply SPL_FAT_SUPPORT
@@ -39,6 +42,7 @@
 	imply SPL_LIBDISK_SUPPORT
 	imply SPL_LIBGENERIC_SUPPORT
 	imply SPL_MMC_SUPPORT
+	imply SPL_NAND_SIMPLE
 	imply SPL_NAND_SUPPORT
 	imply SPL_POWER_SUPPORT
 	imply SPL_SERIAL_SUPPORT
@@ -49,6 +53,8 @@
 	bool "OMAP54XX SoC"
 	select ARM_ERRATA_798870
 	select SYS_THUMB_BUILD
+	imply NAND_OMAP_ELM
+	imply NAND_OMAP_GPMC
 	imply SPL_DISPLAY_PRINT
 	imply SPL_ENV_SUPPORT
 	imply SPL_EXT_SUPPORT
@@ -59,6 +65,8 @@
 	imply SPL_LIBDISK_SUPPORT
 	imply SPL_LIBGENERIC_SUPPORT
 	imply SPL_MMC_SUPPORT
+	imply SPL_NAND_AM33XX_BCH
+	imply SPL_NAND_AM33XX_BCH
 	imply SPL_NAND_SUPPORT
 	imply SPL_POWER_SUPPORT
 	imply SPL_SERIAL_SUPPORT
@@ -73,6 +81,8 @@
 
 config TI816X
 	bool "TI816X SoC"
+	imply NAND_OMAP_ELM
+	imply NAND_OMAP_GPMC
 	help
 	  Support for AM335x SOC from Texas Instruments.
 	  The AM335x high performance SOC features a Cortex-A8
@@ -80,8 +90,12 @@
 
 config AM43XX
 	bool "AM43XX SoC"
+	imply NAND_OMAP_ELM
+	imply NAND_OMAP_GPMC
 	imply SPL_DM
 	imply SPL_DM_SEQ_ALIAS
+	imply SPL_NAND_AM33XX_BCH
+	imply SPL_NAND_SUPPORT
 	imply SPL_OF_CONTROL
 	imply SPL_OF_TRANSLATE
 	imply SPL_SEPARATE_BSS
@@ -97,6 +111,10 @@
 
 config AM33XX
 	bool "AM33XX SoC"
+	imply NAND_OMAP_ELM
+	imply NAND_OMAP_GPMC
+	imply SPL_NAND_AM33XX_BCH
+	imply SPL_NAND_SUPPORT
 	imply SYS_I2C_OMAP24XX
 	imply SYS_THUMB_BUILD
 	imply USE_TINY_PRINTF