arm: dts: k3-am642: Update main_bcdma and main_pktdma nodes

Update main_bcdma and main_pktdma nodes for native configuration in the
absence of DM services.

Drop duplicate main_pktdma node in k3-am642-sk-u-boot.dtsi.

Reported-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Nishanth Menon <nm@ti.com>