[Comgr][NFC] Add TODO for addressable to available VGPR metadata

We should change this at a later point if we are introducing other
breaking changes to the metadata field names

Author: lamb-j

amd/comgr/src/comgr-metadata.cpp

@@ -352,6 +352,7 @@ struct IsaInfo {
   unsigned AddressableNumSGPRs;
   unsigned VGPRAllocGranule;
   unsigned TotalNumVGPRs;
+  // TODO: Update this to AvailableNumVGPRs to be more accurate
   unsigned AddressableNumVGPRs;
 } IsaInfos[] = {
 #define HANDLE_ISA(TARGET_TRIPLE, PROCESSOR, SRAMECC_SUPPORTED,                \