arm64: dts: ti: am64-phyboard-electra: Add DT overlay for X27 connector

Add a device tree overlay for SPI1 , UART3 and GPIO1 on
X27 connector.

By default, not all interfaces on the X27 connector are accessible
due to being disabled or set to alternative pin mux configurations.
This overlay activates and configures these interfaces to support
connections with external devices.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Link: https://lore.kernel.org/r/20250128100356.462934-1-d.schultz@phytec.de


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