This fixes the following CACHE warnings when using sun8i_emac:

=> dhcp
BOOTP broadcast 1
BOOTP broadcast 2
CACHE: Misaligned operation at range [7bf594a8, 7bf59628]
BOOTP broadcast 3
CACHE: Misaligned operation at range [7bf59c90, 7bf59e10]
CACHE: Misaligned operation at range [7bf5a478, 7bf5a5f8]
DHCP client bound to address 10.42.43.80 (1009 ms)

Note this commit also changes the max rx size from 2024 to 2044,
matching what the kernel driver uses.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Corentin LABBE <clabbe.montjoie@gmail.com>
Cc: Amit Singh Tomar <amittomer25@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>