Fix spelling

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Haakan T Johansson <f96hajo@chalmers.se>
Closes #5547 
Closes #5543

module/zfs/zfs_rlock.c

@@ -65,7 +65,7 @@
  * Otherwise, the proxy lock is split into smaller lock ranges and
  * new proxy locks created for non overlapping ranges.
  * The reference counts are adjusted accordingly.
- * Meanwhile, the orginal lock is kept around (this is the callers handle)
+ * Meanwhile, the original lock is kept around (this is the callers handle)
  * and its offset and length are used when releasing the lock.
  *
  * Thread coordination
@@ -87,7 +87,7 @@
  *
  * Grow block handling
  * -------------------
- * ZFS supports multiple block sizes currently upto 128K. The smallest
+ * ZFS supports multiple block sizes currently up to 128K. The smallest
  * block size is used for the file which is grown as needed. During this
  * growth all other writers and readers must be excluded.
  * So if the block size needs to be grown then the whole file is