kernel: generic: tg3: Fix DMA allocations on 57766 devices

kernel: generic: tg3: Fix DMA allocations on 57766 devices

At the request of rsalvaterra, add this patch to fix an issue
affecting tg3 ethernet interfaces[1].

1. https://github.com/openwrt/openwrt/pull/17271#issuecomment-2543836518

Tested-by: Rui Salvaterra <rsalvaterra@gmail.com>
Signed-off-by: John Audia <therealgraysky@proton.me>
Link: https://github.com/openwrt/openwrt/pull/17282
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit a3c484c3b9468a7bd9190b0fee027bb133cee3d5)