[AMDGPU] Use SOP_Pseudo more consistently. NFC.

[foad]

Summary

SOPK_Pseudo was not inheriting from SOP_Pseudo at all, and some other
Pseudo classes were needlessly redefining things that were already
defined by SOP_Pseudo.

[dp]

LGTM.

llvm/lib/Target/AMDGPU/SOPInstructions.td

class SOP1_Pseudo <string opName, dag outs, dag ins,
   let hasSideEffects = 0;
   let SALU = 1;
   let SOP1 = 1;
   let SchedRW = [WriteSALU];
   let Size = 4;
   let UseNamedOperandTable = 1;
 
   bits<1> has_src0 = 1;
-  bits<1> has_sdst = 1;
+  let has_sdst = 1;
 }
 
 class SOP1_Real<bits<8> op, SOP1_Pseudo ps, string real_name = ps.Mnemonic> :
   InstSI <ps.OutOperandList, ps.InOperandList,
           real_name # ps.AsmOperands>,
   Enc32 {
 
   let SALU = 1;

 } // End SubtargetPredicate = isGFX11Plus
 
 //===----------------------------------------------------------------------===//
 // SOPK Instructions
 //===----------------------------------------------------------------------===//
 
 class SOPK_Pseudo <string opName, dag outs, dag ins,
                    string asmOps, list<dag> pattern=[]> :
-  InstSI <outs, ins, "", pattern>,
-  SIMCInstr<opName, SIEncodingFamily.NONE> {
-  let isPseudo = 1;
-  let isCodeGenOnly = 1;
+  SOP_Pseudo<opName, outs, ins, " " # asmOps, pattern> {
   let mayLoad = 0;
   let mayStore = 0;
   let hasSideEffects = 0;
   let SALU = 1;
   let SOPK = 1;
   let FixedSize = 1;
   let SchedRW = [WriteSALU];
   let UseNamedOperandTable = 1;
-  string Mnemonic = opName;
-  string AsmOperands = " " # asmOps;
 
-  bits<1> has_sdst = 1;
+  let has_sdst = 1;
 }
 
 class SOPK_Real<SOPK_Pseudo ps> :
   InstSI <ps.OutOperandList, ps.InOperandList,
           ps.Mnemonic # ps.AsmOperands> {
   let SALU = 1;
   let SOPK = 1;
   let isPseudo = 0;

 // SOPP Instructions
 //===----------------------------------------------------------------------===//
 
 class SOPP_Pseudo<string opName, dag ins,
                   string asmOps = "", list<dag> pattern=[],
                   string sep = !if(!empty(asmOps), "", " "),
                   string keyName = opName> :
   SOP_Pseudo<opName, (outs), ins, sep # asmOps, pattern> {
-  let isPseudo = 1;
-  let isCodeGenOnly = 1;
   let mayLoad = 0;
   let mayStore = 0;
   let hasSideEffects = 0;
   let SALU = 1;
   let SOPP = 1;
   let FixedSize = 1;
   let SchedRW = [WriteSALU];
   let UseNamedOperandTable = 1;