[media] blackfin: check devm_pinctrl_get() for errors

devm_pinctrl_get() can fail so we should check for that.

Fixes: 0a6824bc

 ('[media] v4l2: blackfin: select proper pinctrl state in ppi_set_params if CONFIG_PINCTRL is enabled')

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>