arm64: dts: ti: k3-am642-evm: Add support for SPI EEPROM

Add pinmux details and device tree node for the EEPROM attached to SPI0
module in main domain.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20210309162315.22743-1-a-govindraju@ti.com