ARM: dts: at91: sama7g5: add cells for temperature calibration

Add NVMEM cell to ADC for temperature calibration data.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20221026124114.985876-5-claudiu.beznea@microchip.com