Driver bails out with -EINVAL when no polling specififaion is requested.
Fix that by verifing polling interval only if polling_mode is different
from CM_POLL_DISABLE.
Signed-off-by: NLadislav Michl <ladis@linux-mips.org>
Signed-off-by: NSebastian Reichel <sebastian.reichel@collabora.co.uk>