Drop obsolete sigops comment

This comment was confusing and incorrect when first added ("invalid rather than
merely non-standard" has the opposite meaning of what is actually the case),
and was also not updated after segwit with the correct variable names.

Delete it since the code reads just fine on its own.

Co-authored by: Anthony Towns <aj@erisian.com.au>
                Suhas Daftuar <sdaftuar@gmail.com>

src/validation.cpp

@@ -721,11 +721,6 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                               fSpendsCoinbase, nSigOpsCost, lp);
         unsigned int nSize = entry.GetTxSize();
 
-        // Check that the transaction doesn't have an excessive number of
-        // sigops, making it impossible to mine. Since the coinbase transaction
-        // itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
-        // MAX_BLOCK_SIGOPS; we still consider this an invalid rather than
-        // merely non-standard transaction.
         if (nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST)
             return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
                 strprintf("%d", nSigOpsCost));