Revert "net: ethernet: bgmac: Use devm_platform_ioremap_resource_byname"

This reverts commit 3710e809.

Since idm_base and nicpm_base are still optional resources not present
on all platforms, this breaks the driver for everything except Northstar
2 (which has both).

The same change was already reverted once with 755f5738 ("net:
broadcom: fix a mistake about ioremap resource").

So let's do it again.

Fixes: 3710e809 ("net: ethernet: bgmac: Use devm_platform_ioremap_resource_byname")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
[florian: Added comments to explain the resources are optional]
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220216184634.2032460-1-f.fainelli@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>