Merge branch 'net-stmmac-dwmac-anarion-address-issues-flagged-by-sparse'

Simon Horman says:

====================
net: stmmac: dwmac-anarion: address issues flagged by sparse

Two minor enhancements to dwmac-anarion to address issues flagged by
sparse.

1. Always return struct anarion_gmac * from anarion_config_dt()
2. Add __iomem annotation to register base

No functional change intended.
Compile tested only.
====================

Link: https://lore.kernel.org/r/20230406-dwmac-anarion-sparse-v1-0-b0c866c8be9d@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>