Docs., error checking and test improvements

* Update doc. on api-support function
* Check for valid integer value when reading a monitor int. val.
* If fan-write test attempts to set speed higher than max.
   possible, then skip the test

Change-Id: I01ad0ab1f4caffdb0d2c26e9575f278c35a6b017

include/rocm_smi/rocm_smi.h

@@ -2636,6 +2636,12 @@ rsmi_dev_xgmi_error_reset(uint32_t dv_ind);
  * iterator handle to the caller-provided memory pointed to by @p handle. This
  * handle can be used to iterate through all the supported functions.
  *
+ * Note that although this function takes in @p dv_ind as an argument,
+ * ::rsmi_dev_supported_func_iterator_open itself will not be among the
+ * functions listed as supported. This is because
+ * ::rsmi_dev_supported_func_iterator_open does not depend on hardware or
+ * driver support and should always be supported.
+ *
  * @param[in] dv_ind a device index of device for which support information is
  * requested
  *

include/rocm_smi/rocm_smi_utils.h

@@ -69,6 +69,8 @@ int isRegularFile(std::string fname, bool *is_reg);
 int ReadSysfsStr(std::string path, std::string *retStr);
 int WriteSysfsStr(std::string path, std::string val);
 
+bool IsInteger(const std::string & n_str);
+
 struct pthread_wrap {
  public:
         explicit pthread_wrap(pthread_mutex_t &p_mut) : mutex_(p_mut) {}