net: ethernet: ti: am65-cpsw-nuss: cleanup DMA Channels before using them

The TX and RX DMA Channels used by the driver to exchange data with CPSW
are not guaranteed to be in a clean state during driver initialization.
The Bootloader could have used the same DMA Channels without cleaning them
up in the event of failure. Thus, reset and disable the DMA Channels to
ensure that they are in a clean state before using them.

Fixes: 93a76530

 ("net: ethernet: ti: introduce am65x/j721e gigabit eth subsystem driver")
Reported-by: Schuyler Patton <spatton@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20240417095425.2253876-1-s-vadapalli@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>