Allow device parameters for devices with dots in name
Devices can have a dot in the name, so we can't expect to find the
full device name before the first dot. Currently parameters of devices
with a dot in the name are inaccessible from the shell.
Fix this by iterating over the possible device name / parameter name
combinations to find a existing combination.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>