net: ethernet: litex: Add the dependency on HAS_IOMEM

net: ethernet: litex: Add the dependency on HAS_IOMEM

[ Upstream commit 2427f03fb42f9dc14c53108f2c9b5563eb37e770 ]

The LiteX driver uses devm io function API which
needs HAS_IOMEM enabled, so add the dependency on HAS_IOMEM.

Fixes: ee7da21ac4c3 ("net: Add driver for LiteX's LiteETH network interface")
Signed-off-by: Cai Huoqing <cai.huoqing@linux.dev>
Link: https://lore.kernel.org/r/20220208013308.6563-1-cai.huoqing@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>