[NFC][NVPTX] Remove dead comment and commented code

[ldrumm]

Summary

A confusing comment after the last return statement in
NVPTXAsmPrinter::doFinalization referred to a preprocessor macro
(NVISA) that has never existed since the NVPTX backend has been a part
of upstream llvm - as far as the pickaxe will tell me anyway. Thus I've
removed it.

llvm/lib/Target/NVPTX/NVPTXAsmPrinter.cpp

if (HasDebugInfo) {
     // Emit empty .debug_loc section for better support of the empty files.
     OutStreamer->emitRawText("\t.section\t.debug_loc\t{\t}");
   }
 
   // Output last DWARF .file directives, if any.
   TS->outputDwarfFileDirectives();
 
   return ret;
-
-  //bool Result = AsmPrinter::doFinalization(M);
-  // Instead of calling the parents doFinalization, we may
-  // clone parents doFinalization and customize here.
-  // Currently, we if NVISA out the EmitGlobals() in
-  // parent's doFinalization, which is too intrusive.
-  //
-  // Same for the doInitialization.
-  //return Result;
 }
 
 // This function emits appropriate linkage directives for
 // functions and global variables.
 //
 // extern function declaration            -> .extern
 // extern function definition             -> .visible
 // external global variable with init     -> .visible