mtd: nand: omap_gpmc: Fix 'bit-flip' errors

OMAP GPMC driver used with some NAND Flash devices (e.g. Spansion
S34ML08G1) causes that U-boot shows hundreds of 'nand: bit-flip
corrected' error messages. Possible cause was discussed in the
mailinglist thread:
http://lists.denx.de/pipermail/u-boot/2014-April/177508.html

Quote (Author: Pekon Gupta <pekon@ti.com>): "The issue is mainly
due to a NAND protocol violation in the omap driver since the
Random Data Output command (05h-E0h) expects to see only the
column address that should be addressed within the already loaded
read page into the read buffer. Only 2 address cycles with ALE
active should be provided between the 05h and E0h commands. The
Page read command expects the full address footprint (2bytes for
column address + 3bytes for row address), but once the page is
loaded into the read buffer, Random Data Output should be used
with only 2bytes for column address."

This patch combines the solution proposed in the mailinglist and
the patch provided by the Spansion company (GPLv2 code, source:
http://www.spansion.com/Support/Software/u-boot-psp-04.04.00.01-NAND.zip

)

Signed-off-by: Rostislav Lisovy <lisovy@merica.cz>