HID: sony: Use __u8 * for the buffer in sixaxis_set_operational_usb()

Use the same type declared in the prototypes of functions that are going
to accept the buffer as parameter.

Signed-off-by: Antonio Ospite <ao2@ao2.it>
Acked-by: Frank Praznik <frank.praznik@oh.rr.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>