nvmem: fix memory leak in error path

We need to free the ida mapping and nvmem struct if the write-protect
GPIO lookup fails.

Fixes: 2a127da4

 ("nvmem: add support for the write-protect pin")
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200310132257.23358-7-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>