ARM: sun7i: Fix i2c4 base address

For some reason, the base address of the fifth I2C adapter in the A20 was
incorrect. Change this to the actual base address.

Reported-by: Marcus Cooper <codekipper@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
ARM: sunxi: Enable GMAC in sunxi_defconfig

Since the support of the GMAC has been merged, we're using it as the ethernet
controller on the A20 devices.

However, sunxi_defconfig wasn't selecting it hence breaking the NFS boot.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>