The devm_ioremap() function returns NULL on error, it doesn't return
error pointers.
Fixes: 3a1a274e93 ("mlxbf_gige: compute MDIO period based on i1clk")
Signed-off-by: Peng Wu <wupeng58@huawei.com>
Link: https://lore.kernel.org/r/20220923023640.116057-1-wupeng58@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>