net: socionext: include linux/io.h to fix build

I ran into a randconfig build failure:

drivers/net/ethernet/socionext/netsec.c: In function 'netsec_probe':
drivers/net/ethernet/socionext/netsec.c:1583:17: error: implicit declaration of function 'devm_ioremap'; did you mean 'ioremap'? [-Werror=implicit-function-declaration]

Including linux/io.h directly fixes this.

Fixes: 533dd11a ("net: socionext: Add Synquacer NetSec driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>