Fix various typos

Correct an assortment of typos throughout the code base.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Closes #11774

tests/zfs-tests/cmd/file_write/file_write.c

@@ -44,7 +44,7 @@ static unsigned char bigbuffer[BIGBUFFERSIZE];
 static void usage(char *);
 
 /*
- * psudo-randomize the buffer
+ * pseudo-randomize the buffer
  */
 static void randomize_buffer(int block_size) {
 	int i;