nvmem: prefix all symbols with NVMEM_

This unifies all NVMEM symbols. They follow one style now.

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220916122100.170016-8-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>