Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

drivers/char/agp/amd-k7-agp.c

@@ -272,7 +272,7 @@ static void amd_irongate_cleanup(void)
  * This routine could be implemented by taking the addresses
  * written to the GATT, and flushing them individually.  However
  * currently it just flushes the whole table.  Which is probably
- * more efficent, since agp_memory blocks can be a large number of
+ * more efficient, since agp_memory blocks can be a large number of
  * entries.
  */