HID: playstation: fix free of uninialized pointer for DS4 in Bluetooth.

The 'buf' variable is only used in the USB (if-path) and not in the Bluetooth
else-path. Since it is not set to NULL. this results in freeing an uninitialized
pointer. Since the else code-path doesn't need buf, just return 0.

Fixes: 2d77474a ("HID: playstation: add DualShock4 bluetooth support.")
Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20221213044935.1775499-2-roderick.colenbrander@sony.com