nvmem: core: Deduplicate bus_find_device() by name matching

No need to reinvent the wheel, we have bus_find_device_by_name().

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>