UPSTREAM: HID: playstation: fix unused variable in ps_battery_get_property.

The ret variable in ps_battery_get_property is set in an error path,
but never actually returned. Change the function to return ret.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Bug: 167947264
Change-Id: Ieeaff4d249a6ee6d02eb4746f9fe502c91c6f40a
(cherry picked from commit 5fb52551248f54ddc8f72bc252661468b603cfcc)
Signed-off-by: Farid Chahla <farid.chahla@sony.com>