mtd: rawnand: omap_gpmc: Use DT provided IO address

For DM case we can get the NAND chip's IO address from DT
so we don't need to rely on CFG_SYS_NAND_BASE.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://www.mail-archive.com/u-boot@lists.denx.de/msg499177.html


Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>