Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b61ebec..bd0806e 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1055,7 +1055,7 @@
  *	@arg: this is third argument given to ioctl(2) system call.
  *	Often contains a pointer.
  *
- *	Returns 0 if successful (some ioctls return postive numbers on
+ *	Returns 0 if successful (some ioctls return positive numbers on
  *	success as well). Returns a negated errno value in case of error.
  *
  *	Note: most ioctls are forward onto the block subsystem or further