arm64: dts: broadcom: bcmbca: bcm4908: use NVMEM layout for Asus GT-AC5300

Defining NVMEM cells as direct subnodes is deprecated since commit
bd912c99

 ("dt-bindings: nvmem: layouts: add fixed-layout"). Use new
syntax based on NVMEM layout.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20240111115617.12072-1-zajec5@gmail.com


Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>