Crazy things happen if there are resource conflicts and a device probe
runs dev_request_mem_region. The dev_request_mem_region returns a
start pointer which is zero. The probe function doesn't check on this
and probing the device on zero base address.

To debug this in debug log level there are many other outputs. This patch
replace the debug print to a warning printout. A conflict should
normally never happen. If there is a conflict it's much easier to see it
with this patch.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>