HID: nvidia-shield: Add missing check for input_ff_create_memless

Add check for the return value of input_ff_create_memless() and return
the error if it fails in order to catch the error.

Fixes: 09308562

 ("HID: nvidia-shield: Initial driver implementation with Thunderstrike support")
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Reviewed-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>