HID: fix unused rsize usage

commit bc197eedef1ae082ec662c64c3f4aa302821fb7a upstream.

27ce4050 ("HID: fix data access in implement()") by mistake removed
a setting of buffer size in hidp. Fix that by putting it back.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>