Check return value from call to of_match_device()
in order to prevent a NULL pointer dereference.

In case of NULL print error message and return -ENODEV
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>