net: mtk: wed: add dma mask limitation and GFP_DMA32 for device with more than 4GB DRAM

Limit tx/rx buffer address to 32-bit address space for board with more
than 4GB DRAM.

Fixes: 804775df ("net: ethernet: mtk_eth_soc: add support for Wireless Ethernet Dispatch (WED)")
Fixes: 6757d345 ("net: ethernet: mtk_wed: introduce hw_rro support for MT7988")
Tested-by: Daniel Pawlik <pawlik.dan@gmail.com>
Tested-by: Matteo Croce <teknoraver@meta.com>
Signed-off-by: Rex Lu <rex.lu@mediatek.com>
Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>