Resume or suspend each sensor device based on the num_hid_devices.
Therefore, add a check to handle the special case where no sensors are
present.

Fixes: 93ce5e02 ("HID: amd_sfh: Implement SFH1.1 functionality")
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>