arm64: dts: ti: k3-am6xx-phycore-som: Add overlay to disable spi nor

Add an overlay to disable the spi nor for all am6xx-phycore-som
boards.
The EEPROM on am6xx-phycore-soms contains information about the
configuration of the SOM. The standard configuration of the SOM
has an ospi nor, but if no nor is populated, the EEPROM will indicate
that change and we can use this overlay to cleanly disable the
spi nor.

Signed-off-by: Nathan Morrisson <nmorrisson@phytec.com>
Link: https://lore.kernel.org/r/20240613230759.1984966-5-nmorrisson@phytec.com


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