net: sun4i-emac: Properly free resources on probe failure and remove

Fix sun4i-emac not releasing the following resources:
-iomapped memory not released on probe-failure nor on remove
-clock not getting disabled on probe-failure nor on remove
-sram not being released on remove

And while at it also add error checking to the clk_prepare_enable call
done on probe.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>