Lucas Stach authored May 02, 2019 and Ezequiel Garcia committed Feb 13, 2020

Peripherals on i.MX8M are unable to DMA to memory above the 4GB mark.
This leads to reduced performance due to bounce buffering, or complete
system failure if there is not enough bounce buffer space available.

As the network RX buffer rings constitute a fair amount of DMA mapped
memory, make sure to get them from the DMA32 zone, to avoid any bounce
buffering.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>