Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

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

drivers/gpu/drm/mga/mga_dma.c

@@ -426,7 +426,7 @@ int mga_driver_load(struct drm_device *dev, unsigned long flags)
  * Bootstrap the driver for AGP DMA.
  *
  * \todo
- * Investigate whether there is any benifit to storing the WARP microcode in
+ * Investigate whether there is any benefit to storing the WARP microcode in
  * AGP memory.  If not, the microcode may as well always be put in PCI
  * memory.
  *