arm64: dts: ti: k3-am62a7-sk: Describe main_uart1 and wkup_uart

wkup_uart and main_uart1 on this platform is used by tifs and DM
firmwares. Describe them for completeness including the pinmux.

Signed-off-by: Nishanth Menon <nm@ti.com>
[bb@ti.com: updated pinmux and commit subject]
Signed-off-by: Bryan Brattlof <bb@ti.com>
Link: https://lore.kernel.org/r/20230425221708.549675-1-bb@ti.com


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>