nvmem: meson-efuse: add error message on user_max failure.

Add an explicit error message when SM_EFUSE_USER_MAX command fails

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>