SWDEV-450580 - Fix powercap set

Updates:
     * CLI - Added AMDSMIHelpers.convert_SI_unit() to help
       conversion of units
     * API - Reverted to uW for power cap limits
     * CLI - amd-smi static --limit now includes MIN_POWER
     * Tests now are all using uW units to keep W conversion
       to only happen in CLI
     * Python API now reflects same units as uW (what is seen
       in amdgpu driver)
     * CLI - amd-smi metric --power:
       Fixed power seen on gpu_metrics v1.3

Change-Id: I32d9ba78d0d8806772f0860f9a803a885b3f316a
Signed-off-by: Charis Poag <Charis.Poag@amd.com>

example/amd_smi_drm_example.cc

@@ -657,15 +657,15 @@ int main() {
             CHK_AMDSMI_RET(ret)
             printf("    Output of amdsmi_get_power_cap_info:\n");
             std::cout << "\t\t Power Cap: " << cap_info.power_cap
-                      << "W\n";
+                      << " uW\n";
             std::cout << "\t\t Default Power Cap: " << cap_info.default_power_cap
-                      << "\n\n";
+                      << " uW\n\n";
             std::cout << "\t\t Dpm Cap: " << cap_info.dpm_cap
-                      << "\n\n";
+                      << " MHz\n\n";
             std::cout << "\t\t Min Power Cap: " << cap_info.min_power_cap
-                      << "\n\n";
+                      << " uW\n\n";
             std::cout << "\t\t Max Power Cap: " << cap_info.max_power_cap
-                      << "\n\n";
+                      << " uW\n\n";
 
             /// Get GPU Metrics info
             std::cout << "\n\n";