net: ep93xx_eth: fix mismatch of request_mem_region in remove

The driver calls release_resource in remove to match request_mem_region
in probe, which is incorrect.
Fix it by using the right one, release_mem_region.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>