ARM: dts: microchip: at91-sama7g5ek: add EEPROMs

The main boot sequence for Microchip AT91 devices is one of the
following:
1/ ROM BOOT -> AT91Bootstrap -> U-Boot -> Linux Kernel
2/ ROM BOOT -> AT91Bootstrap -> Linux Kernel

For case 1/ U-Boot is the stage where the Ethernet MAC addresses are set.
For case 2/ where U-Boot is skipped the Ethernet MAC addresses need to
be configured in Linux. For this add EEPROMs and nvmem-layout to describe
EUI48 MAC address regions.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
[andrei.simion@microchip.com: Add nvmem-layout to describe eui48 mac
 region. Align compatible name with datasheet. Reword commit message.]
Signed-off-by: Andrei Simion <andrei.simion@microchip.com>
[claudiu.beznea: adjusted the new commit message]
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Link: https://lore.kernel.org/r/20240703084704.197697-3-andrei.simion@microchip.com