mmc: omap_hsmmc: ensure probe returns error upon resource failure

mmc: omap_hsmmc: ensure probe returns error upon resource failure

If platform_get_resource_by_name() fails, driver probe is aborted an
should return an error so the driver is not bound to the device.

However, in the current error path of platform_get_resource_by_name(),
probe returns zero since the return value (ret) is not properly set.
With a zero return value, the driver core assumes probe was successful
and will bind the driver to the device.

Fix this by ensuring that probe returns an error code in this failure
path.

Signed-off-by: Kevin Hilman <khilman@ti.com>
Acked-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>