Remove mutex on TSMWriter
Remove mutex on TSMWriter

This isn't used by more than one goroutine so locks are unnecessary.

influxdata/influxdb,nooproblem/influxdb,mark-rushakoff/influxdb,nooproblem/influxdb,vladlopes/influxdb,li-ang/influxdb,li-ang/influxdb,benbjohnson/influxdb,linearb/influxdb,influxdb/influxdb,vladlopes/influxdb,benbjohnson/influxdb,linearb/influxdb,linearb/influxdb,nooproblem/influxdb,nooproblem/influxdb,mark-rushakoff/influxdb,influxdb/influxdb,influxdb/influxdb,influxdb/influxdb,mark-rushakoff/influxdb,mark-rushakoff/influxdb,vladlopes/influxdb,mark-rushakoff/influxdb,vladlopes/influxdb,nooproblem/influxdb,benbjohnson/influxdb,influxdb/influxdb,influxdata/influxdb,linearb/influxdb,influxdb/influxdb,mark-rushakoff/influxdb,benbjohnson/influxdb,linearb/influxdb