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>

bus: Add imx-weim support ...

Mostly taken from the kernel with support for other SoCs from
Alexander Shiyan.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alexander Shiyan <shc_work@mail.ru>