[MC] Don't print () around $ names

This MIPS behavior from edb9d84 (2010)
is obsoleted and misleading. This caused confusion in
https://reviews.llvm.org/D123702 ([NVPTX] Disable parens for identifiers
starting with '$')

Note: $tmp was rejected by AsmParser before
https://reviews.llvm.org/D75111 (2020)

Author: MaskRay

llvm/include/llvm/MC/MCAsmInfo.h

@@ -650,9 +650,6 @@ class MCAsmInfo {
   bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
   bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
   bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
-  bool useParensForDollarSignNames() const {
-    return UseParensForDollarSignNames;
-  }
   bool supportsExtendedDwarfLocDirective() const {
     return SupportsExtendedDwarfLocDirective;
   }

llvm/include/llvm/MC/MCExpr.h

@@ -81,8 +81,7 @@ class MCExpr {
   /// \name Utility Methods
   /// @{
 
-  void print(raw_ostream &OS, const MCAsmInfo *MAI,
-             bool InParens = false) const;
+  void print(raw_ostream &OS, const MCAsmInfo *MAI) const;
   void dump() const;
 
   /// Returns whether the given symbol is used anywhere in the expression or