Allow user to override the default driver timeout for controller ready.

There are some rare configurations which require the driver to wait longer
than the normal 3 minutes for the controller to complete its bootup
sequence and be ready to accept commands from the driver.

The module parameter is:

ctrl_ready_timeout= { 0 | 30-1800 }

and specifies the timeout in seconds for the driver to wait for controller
ready. The valid range is 0 or 30-1800. The default value is 0, which
causes the driver to use a timeout of 180 seconds (3 minutes).

Link: https://lore.kernel.org/r/165730607666.177165.9221211345284471213.stgit@brunhildaReviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Signed-off-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>