SWDEV-508776 - support VGPRs validation (#274)

Clarify some VGPRs terms description.
Fix some wrong query logics of availableVGPRs_ and
availableRegistersPerCU_ in device info.
Add hipDeviceAttributeMaxAvailableVgprsPerThread
attribute query.
Remove hardcoding of following
 info_.vgprAllocGranularity_
 info_.vgprsPerSimd_

hipamd/src/hip_platform.cpp

@@ -397,7 +397,7 @@ hipError_t ihipOccupancyMaxActiveBlocksPerMultiprocessor(
   }
 
   if (VgprWaves == 0) {
-    // This should not happen ideally, but in case the usedVGPRs_/availableVGPRs_ values are
+    // This should not happen ideally, but in case the value is
     // incorrect, it can lead to a crash. By returning error, API can exit gracefully.
     return hipErrorUnknown;
   }