AMDGPU: Assume true in getVOPNIsSingle helpers (#98516)

If we have something we don't know what it is, we should conservatively
avoid printing an additional suffix. For isCodeGenOnly
pseudoinstructions,
no encoded instruction is added to the tables this is queried, and the
null
case would assume true.

This happens to fix the case I ran into, but this isn't a wholistic fix.
These really should be encoded directly in the TSFlags of the
MCInstrDesc,
which would allow encoding pseudos to work correctly.

Author: arsenm

llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp

@@ -496,17 +496,17 @@ bool getSMEMIsBuffer(unsigned Opc) {
 
 bool getVOP1IsSingle(unsigned Opc) {
   const VOPInfo *Info = getVOP1OpcodeHelper(Opc);
-  return Info ? Info->IsSingle : false;
+  return Info ? Info->IsSingle : true;
 }
 
 bool getVOP2IsSingle(unsigned Opc) {
   const VOPInfo *Info = getVOP2OpcodeHelper(Opc);
-  return Info ? Info->IsSingle : false;
+  return Info ? Info->IsSingle : true;
 }
 
 bool getVOP3IsSingle(unsigned Opc) {
   const VOPInfo *Info = getVOP3OpcodeHelper(Opc);
-  return Info ? Info->IsSingle : false;
+  return Info ? Info->IsSingle : true;
 }
 
 bool isVOPC64DPP(unsigned Opc) {