HID: amd_sfh: Add NULL check for hid device

On removal of hid device during SFH set report may cause NULL pointer
exception. Hence add NULL check for hid device before accessing.

Fixes: 4b2c53d9 ("SFH:Transport Driver to add support of AMD Sensor Fusion Hub (SFH)")
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>