[ARM] pxa: factor pxamci gpio handling

Several boards use always the same pattern with pxamci :
request gpio, request irq for that gpio to detect MMC card
insertion, request gpio for read-only mode detection, etc
...

Now that pxamci provides platform_data to describe simple
gpio management of the MMC external controls, use it.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Mike Rapoport <mike@compulab.co.il>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Acked-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: rpurdie@rpsys.net
Cc: drwyrm@gmail.com
Cc: sakoman@gmail.com
Cc: marek.vasut@gmail.com
Cc: s.hauer@pengutronix.de
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>