docs: nvmem: remove function parameters (fixes hyperlink generation)

Adding a parameter is not particularly useful here, and it is definitely
not done elsewhere. It also prevents the generation of a hyperlink to the
kernel-doc documentation. Removing the parameter to enable hyperlinks and
make the style coherent.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231201-nvmem-docs-kerneldoc-v1-2-3e8f2b706ce6@bootlin.com