memory: omap-gpmc: Fix omap gpmc EXTRADELAY timing

In the omap gpmc driver it can be noticed that GPMC_CONFIG4_OEEXTRADELAY
is overwritten by the WEEXTRADELAY value from the device tree and
GPMC_CONFIG4_WEEXTRADELAY is not updated by the value from the device
tree.

As a consequence, the memory accesses cannot be configured properly when
the extra delay are needed for OE and WE.

Fix the update of GPMC_CONFIG4_WEEXTRADELAY with the value from the
device tree file and prevents GPMC_CONFIG4_OEXTRADELAY
being overwritten by the WEXTRADELAY value from the device tree.

Cc: stable@vger.kernel.org
Signed-off-by: Ocquidant, Sebastien <sebastienocquidant@eaton.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>