sparc: i8042-sparcio.h: fix warning

drivers/input/serio/i8042-sparcio.h:95: warning: 'sparc_i8042_driver'
defined but not used

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>