mtd: mxc-nand: Add a timeout when waiting for interrupt

While extending the mxc-nand driver it happend to me a few times that
the device was stuck and this made the machine hang during boot. So
implement a timeout and print a stack trace the first time this happens
to make it debuggable. The return type of the waiting function is also
changed to int to be able to handle the timeout in the caller.

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