[RISCV] Enable PrimaryKeyEarlyOut on RISCVVPseudosTable.

This table is queried in RISCVMCInstLower without knowing
whether the instruction is a vector pseudo. Due to the way the
binary search works, we have to do log2(tablesize) checks just
to determine a non-vector instruction isn't in the table.

Conveniently, all the vector pseudos are pretty tightly
packed within the internal instruction enum. By enabling the
PrimaryKeyEarlyOut, tablegen will emit a check against the
beginning and end of the table before doing the binary search.
This gives a quick early out on the search for the majority
of non-vector instructions.

Differential Revision: https://reviews.llvm.org/D97016

llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td

@@ -402,6 +402,7 @@ def RISCVVPseudosTable : GenericTable {
   let Fields = [ "Pseudo", "BaseInstr" ];
   let PrimaryKey = [ "Pseudo" ];
   let PrimaryKeyName = "getPseudoInfo";
+  let PrimaryKeyEarlyOut = true;
 }
 
 def RISCVVIntrinsicsTable : GenericTable {