net: cadence: Remove Kconfig dependency on ARCH

Remove Kconfig dependency and enable driver for
all ARCHs.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>