[mips] Change Feature-related types from unsigned to uint64_t in MipsAsmParser. No functional changes.

[tomatabacu]

Summary

Found a couple of cases where unsigned was still being used. These two should be the last ones in the (entire) Mips backend.

[dsanders]

LGTM. Don't forget to say 'No functional change'.

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

#include "MipsGenAsmMatcher.inc"
   void selectArch(StringRef ArchFeature) {
     uint64_t FeatureBits = STI.getFeatureBits();
     FeatureBits &= ~MipsAssemblerOptions::AllArchRelatedMask;
     STI.setFeatureBits(FeatureBits);
     setAvailableFeatures(
         ComputeAvailableFeatures(STI.ToggleFeature(ArchFeature)));
   }
 
-  void setFeatureBits(unsigned Feature, StringRef FeatureString) {
+  void setFeatureBits(uint64_t Feature, StringRef FeatureString) {
     if (!(STI.getFeatureBits() & Feature)) {
       setAvailableFeatures(
           ComputeAvailableFeatures(STI.ToggleFeature(FeatureString)));
     }
   }
 
-  void clearFeatureBits(unsigned Feature, StringRef FeatureString) {
+  void clearFeatureBits(uint64_t Feature, StringRef FeatureString) {
     if (STI.getFeatureBits() & Feature) {
       setAvailableFeatures(
           ComputeAvailableFeatures(STI.ToggleFeature(FeatureString)));
     }
   }
 
 public:
   enum MipsMatchResultTy {