This is based on alx driver commit 881d0327 ("net: alx: Work around
the DMA RX overflow issue").

The alx and atl1c drivers had RX overflow error which was why a custom
allocator was created to avoid certain addresses. The simpler workaround
then created for alx driver, but not for atl1c due to lack of tester.

Instead of using a custom allocator, check the allocated skb address and
use skb_reserve() to move away from problematic 0x...fc0 address.

Tested on AR8131 on Acer 4540.
Signed-off-by: Sieng-Piaw Liew <liew.s.piaw@gmail.com>
Link: https://lore.kernel.org/r/20230912010711.12036-1-liew.s.piaw@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>