The EDMA block has a reset line of its own, but the driver asserts it
only at probe and when it rebuilds the rings. qca_edma is built in and
the switch sits on the conduit, so a reboot is the only other way back
to the engine's power-on state. Implement the ethtool reset op for
ETH_RESET_DMA with the rebuild ring resizing already uses.
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Julius Bairaktaris <julius@bairaktaris.de>
Link: https://github.com/openwrt/openwrt/pull/25700
Signed-off-by: Robert Marko <robimarko@gmail.com>