arm: dts: k3-am625-sk-r5/u-boot: Drop duplicate bootph-nodes

Kernel dts import now provides bootph-all and bootph-pre-ram properties
for the properties we have been overriding so far. Drop the same.

While at this enable the DM and TIFS UARTs for programming pinmux
since they are marked reserved by board.dts

Reviewed-by: Dhruva Gole <d-gole@ti.com>
Tested-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>