Fix ROCPROFSYS_AMD_SMI_METRICS parsing (#178)

Fixes a bug where all the `ROCPROFSYSE_AMD_SMI_METRICS` values were being recorded by default.
Fixes bug with the 'all' and 'none' values giving an exception when specified for `ROCPROFSYSE_AMD_SMI_METRICS`.

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Co-authored-by: David Galiffi <David.Galiffi@amd.com>

[ROCm/rocprofiler-systems commit: 8d48048bd3]

projects/rocprofiler-systems/source/lib/core/config.cpp

@@ -623,7 +623,8 @@ configure_settings(bool _init)
 
     ROCPROFSYS_CONFIG_SETTING(std::string, "ROCPROFSYS_AMD_SMI_METRICS",
                               "amd-smi metrics to collect: busy, temp, power, "
-                              "vcn_activity, jpeg_activity, mem_usage",
+                              "vcn_activity, jpeg_activity, mem_usage."
+                              "An empty value implies 'all' and 'none' suppresses all.",
                               "busy, temp, power, mem_usage", "backend", "amd_smi",
                               "rocm", "process_sampling", "advanced");