mtd: mxc-nand: Allow to use column addresses different from 0

The mxc-nand controller works pagewise and so usually only sends
commands to the flash chip with column == 0. A request with column != 0
from the upper layer is then fulfilled by indexing appropriately into the
device's RAM buffer.

To be able to access the ONFI marker at offset 0x20 in reply to the
READID command however it's invalid to read 32 bytes starting from
column 0.

So let the function used to send the address cycles send the column
address actually passed instead of 0 and fix all callers to pass 0
instead appropriately. Also add some warnings in case this patch changes
the drivers semantics.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>