HID: amd_sfh: Remove unused declarations

Commit 4b2c53d9 ("SFH:Transport Driver to add support of AMD Sensor
Fusion Hub (SFH)") declared but never implemented them.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Acked-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>