can: ti_hecc: include linux/io.h

This fixes a build breakage for OMAP3 boards.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: netdev@vger.kernel.org
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>