mtd: eLBC NAND: increase bus timeout to maximum

mtd: eLBC NAND: increase bus timeout to maximum

When a NAND operation is in progress, all other localbus operations
(including NOR flash) will have to wait for access to the bus.  However, the
NAND operation may take longer to complete than the default timeout.  Thus,
if NOR is accessed while a NAND operation is in progress, the NAND operation
will fail.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>