net: bcmgenet: Revert "Use stronger register read/writes to assure ordering"

It turns out after digging deeper into this bug, that it was being
triggered by GCC12 failing to call the bcmgenet_enable_dma()
routine. Given that a gcc12 fix has been merged [1] and the genet
driver now works properly when built with gcc12, this commit should
be reverted.

[1]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105160
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=aabb9a261ef060cf24fd626713f1d7d9df81aa57

Fixes: 8d3ea3d4

 ("net: bcmgenet: Use stronger register read/writes to assure ordering")
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220412210420.1129430-1-jeremy.linton@arm.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>