soc: qcom: socinfo: fix printing of pmic_model

Print sensible string instead of just "(null)" for unknown PMIC models.
Also as we are at it, do not let debugfs handler access past pmic_models
array.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20200525164817.2938638-2-dmitry.baryshkov@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/soc/qcom/socinfo.c

@@ -274,7 +274,10 @@ static int qcom_show_pmic_model(struct seq_file *seq, void *p)
 	if (model < 0)
 		return -EINVAL;
 
-	seq_printf(seq, "%s\n", pmic_models[model]);
+	if (model <= ARRAY_SIZE(pmic_models) && pmic_models[model])
+		seq_printf(seq, "%s\n", pmic_models[model]);
+	else
+		seq_printf(seq, "unknown (%d)\n", model);
 
 	return 0;
 }