consensus/ethash: fixed typo (#16253)

consensus/ethash/consensus.go

@@ -355,7 +355,7 @@ func calcDifficultyByzantium(time uint64, parent *types.Header) *big.Int {
 	if x.Cmp(params.MinimumDifficulty) < 0 {
 		x.Set(params.MinimumDifficulty)
 	}
-	// calculate a fake block numer for the ice-age delay:
+	// calculate a fake block number for the ice-age delay:
 	//   https://github.com/ethereum/EIPs/pull/669
 	//   fake_block_number = min(0, block.number - 3_000_000
 	fakeBlockNumber := new(big.Int)