[RISCV] Remove remapping Zfinx register classes to GPR class in getRegForInlineAsmConstraint. (#164352)

The codegen for Zfinx has been supported. So we don't need to remap
Zfinx register classes to GPR class.

Author: tclin914

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -24044,18 +24044,7 @@ RISCVTargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
     }
   }
 
-  std::pair<Register, const TargetRegisterClass *> Res =
-      TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT);
-
-  // If we picked one of the Zfinx register classes, remap it to the GPR class.
-  // FIXME: When Zfinx is supported in CodeGen this will need to take the
-  // Subtarget into account.
-  if (Res.second == &RISCV::GPRF16RegClass ||
-      Res.second == &RISCV::GPRF32RegClass ||
-      Res.second == &RISCV::GPRPairRegClass)
-    return std::make_pair(Res.first, &RISCV::GPRRegClass);
-
-  return Res;
+  return TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT);
 }
 
 InlineAsm::ConstraintCode