net: dsa: microchip: Drop unused GPIO includes

This driver does not use the old GPIO includes so drop
them.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>