Revert "net: macb: Clean up the .usrio settings in macb_config instances"

Revert "net: macb: Clean up the .usrio settings in macb_config instances"

Commit 0ae998c4efd69 ("net: macb: Clean up the .usrio settings in
macb_config instances") was a misguided attempt to clean up the driver
that actually just propagated problematic code. The default for usrio is
actually no usrio, and already there are issues with people using the
problematically named "macb_default_usrio" on platforms where the usrio
does not have this so-called default behaviour. usrio is platform
specific and using the default at91 usrio settings should be opt-in
only. Revert the "cleanup" patch.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20260325-rundown-unrushed-dd82c9f5c56c@spud
Signed-off-by: Jakub Kicinski <kuba@kernel.org>