[TableGen] Fix incorrect comment. NFC

Author: topperc

llvm/utils/TableGen/DecoderEmitter.cpp

@@ -682,7 +682,7 @@ static void resolveTableFixups(DecoderTable &Table, const FixupList &Fixups,
        I != E; ++I) {
     // Calculate the distance from the byte following the fixup entry byte
     // to the destination. The Target is calculated from after the 24-bit
-    // NumToSkip entry itself, so subtract two  from the displacement here
+    // NumToSkip entry itself, so subtract three from the displacement here
     // to account for that.
     uint32_t FixupIdx = *I;
     uint32_t Delta = DestIdx - FixupIdx - 3;