resource: Let dev_request_mem_region return an error pointer ...

For all users fix or add the error check.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

gpio: omap: Add devicetree probe support ...

This adds devicetree probe support for the OMAP gpio ports and
also makes sure the corresponding platform_devices don't get
registered when they are already present from devicetree.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

gpio: omap: move to drivers/gpio/ ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>