mtd: Add a CONFIG_SPL_MTD_SUPPORT for a more full NAND subsystem in SPL

This mainly converts the am335x_spl_bch driver to the "normal" format
which means a slight change to nand_info within the driver.

Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/spl/Makefile b/spl/Makefile
index 6fec252..a4d9737 100644
--- a/spl/Makefile
+++ b/spl/Makefile
@@ -104,6 +104,7 @@
 libs-y += fs/
 libs-$(CONFIG_SPL_LIBGENERIC_SUPPORT) += lib/
 libs-$(CONFIG_SPL_POWER_SUPPORT) += drivers/power/ drivers/power/pmic/
+libs-$(CONFIG_SPL_MTD_SUPPORT) += drivers/mtd/
 libs-$(if $(CONFIG_CMD_NAND),$(CONFIG_SPL_NAND_SUPPORT)) += drivers/mtd/nand/
 libs-$(CONFIG_SPL_DRIVERS_MISC_SUPPORT) += drivers/misc/
 libs-$(CONFIG_SPL_ONENAND_SUPPORT) += drivers/mtd/onenand/