[RISCV] Remove NotHasStdExtZbb predicate from zext.h/sext.b/sext.h InstAliases. NFC

NotHasStdExtZbb doesn't have an AssemblerPredicate associated with it
so it didn't do anything. We don't need it either because the sorting
rules in tablegen prioritize by number of predicates. So the
dedicated instructions in the B extension that have predicates
will be prioritized automatically.

Author: topperc

llvm/lib/Target/RISCV/RISCV.td

@@ -126,7 +126,6 @@ def HasStdExtZbbOrZbp
                 AssemblerPredicate<(any_of FeatureExtZbb, FeatureExtZbp)>;
 def NotHasStdExtZbbOrZbp
     : Predicate<"!(Subtarget->hasStdExtZbb() || Subtarget->hasStdExtZbp())">;
-def NotHasStdExtZbb : Predicate<"!Subtarget->hasStdExtZbb()">;
 
 def FeatureExtZbproposedc
     : SubtargetFeature<"experimental-zbproposedc", "HasStdExtZbproposedc", "true",

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -1074,19 +1074,19 @@ def PseudoLA_TLS_GD : Pseudo<(outs GPR:$dst), (ins bare_symbol:$src), [],
 
 // There are single-instruction versions of these in Zbb, so disable these
 // Pseudos if that extension is present.
-let Predicates = [NotHasStdExtZbb], hasSideEffects = 0, mayLoad = 0,
+let hasSideEffects = 0, mayLoad = 0,
     mayStore = 0, isCodeGenOnly = 0, isAsmParserOnly = 1 in {
 def PseudoSEXT_B : Pseudo<(outs GPR:$rd), (ins GPR:$rs), [], "sext.b", "$rd, $rs">;
 def PseudoSEXT_H : Pseudo<(outs GPR:$rd), (ins GPR:$rs), [], "sext.h", "$rd, $rs">;
 // rv64's sext.w is defined above, using InstAlias<"sext.w ...
 // zext.b is defined above, using InstAlias<"zext.b ...
 def PseudoZEXT_H : Pseudo<(outs GPR:$rd), (ins GPR:$rs), [], "zext.h", "$rd, $rs">;
-} // Predicates = [NotHasStdExtZbb], ...
+} // hasSideEffects = 0, ...
 
-let Predicates = [NotHasStdExtZbb, IsRV64], hasSideEffects = 0, mayLoad = 0, mayStore = 0,
+let Predicates = [IsRV64], hasSideEffects = 0, mayLoad = 0, mayStore = 0,
   isCodeGenOnly = 0, isAsmParserOnly = 1 in {
 def PseudoZEXT_W : Pseudo<(outs GPR:$rd), (ins GPR:$rs), [], "zext.w", "$rd, $rs">;
-} // Predicates = [NotHasStdExtZbb, IsRV64], ...
+} // Predicates = [IsRV64], ...
 
 /// Loads