arm64: dts: rockchip: mark eeprom as read-only for Radxa E52C

The eeprom on the Radxa E52C SBC contains manufacturer data
such as the mac address, so it should be marked as read-only.

Fixes: 9be41712 ("arm64: dts: rockchip: Add Radxa E52C")
Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Link: https://lore.kernel.org/r/20250810100020.445053-2-amadeus@jmu.edu.cn


Signed-off-by: Heiko Stuebner <heiko@sntech.de>