dt-bindings: nvmem: SID: allow NVMEM cells based on old syntax

dt-bindings: nvmem: SID: allow NVMEM cells based on old syntax

This binding supported NVMEM cells as subnodes and that syntax is used
by few in-kenel DTS files. Modify binding to allow it.

Reported-by: Rob Herring <robh@kernel.org>
Fixes: c5330723d5a0 ("dt-bindings: nvmem: move deprecated cells binding to its own file")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231024171253.19976-1-zajec5@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>