Fix typos

Correct various typos in the comments and tests.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Closes #10423

module/zfs/metaslab.c

@@ -3547,7 +3547,7 @@ metaslab_condense(metaslab_t *msp, dmu_tx_t *tx)
 	 * 4] At this point, we would ideally like to add all segments
 	 *    in the ms_allocatable tree from the condense tree. This way
 	 *    we would write all the entries of the condense tree as the
-	 *    condensed space map, which would only contain freeed
+	 *    condensed space map, which would only contain freed
 	 *    segments with everything else assumed to be allocated.
 	 *
 	 *    Doing so can be prohibitively expensive as ms_allocatable can