SWDEV-1 - Fix incorrect SGPR usage in VGPR calculation. Pointed out by #58 issue on hipamd public repo

Change-Id: I8c27c0da254521714c92369990aa10f6fc09c246

hipamd/src/hip_platform.cpp

@@ -340,7 +340,7 @@ hipError_t ihipOccupancyMaxActiveBlocksPerMultiprocessor(
       VgprGranularity = VgprGranularity >> 1;
     }
   }
-  if (wrkGrpInfo->usedSGPRs_ > 0) {
+  if (wrkGrpInfo->usedVGPRs_ > 0) {
     VgprWaves = maxVGPRs / amd::alignUp(wrkGrpInfo->usedVGPRs_, VgprGranularity);
   }