cleanup: fix typos in mysql/client.go
cleanup: fix typos in mysql/client.go

Signed-off-by: Guangming Wang <2dca52765acf93a024077590b100d00c3300ed67@daocloud.io>
tinyspeck/vitess,vitessio/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,vitessio/vitess,tinyspeck/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,tinyspeck/vitess,mahak/vitess,tinyspeck/vitess,mahak/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,vitessio/vitess,mahak/vitess,mahak/vitess,mahak/vitess,vitessio/vitess,vitessio/vitess