generic: 6.12: update block NVMEM driver

generic: 6.12: update block NVMEM driver

Update block NVMEM driver based on backported OF partition support.

Note the different MMC card DT binding compared to the previous
downstream solution: Instead of having a 'partitions' subnode inside
a 'block' node, the 'partitions' node now resides directly under the
node representing the card.

In order to make references to the 'boot0' or 'boot1' hw partitions
you will have to define 'partitions-boot0' or 'partitions-boot1', and
move the NVMEM layout into a partition (you may, of course, use
'fixed-partitions' for that, and cover the whole device, if needed).

See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/mmc/mmc-card.yaml?h=v6.13

Signed-off-by: Daniel Golle <daniel@makrotopia.org>