nvmem: core: support passing DT node in cell info

Some hardware may have NVMEM cells described in Device Tree using
individual nodes. Let drivers pass such nodes to the NVMEM subsystem so
they can be later used by NVMEM consumers.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220429162701.2222-2-srinivas.kandagatla@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>