Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 4be5879..bdbab5c 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -1492,7 +1492,7 @@
  *
  * \return Flags, or'ed together as follows:
  *
- * DRM_SCANOUTPOS_VALID = Query successfull.
+ * DRM_SCANOUTPOS_VALID = Query successful.
  * DRM_SCANOUTPOS_INVBL = Inside vblank.
  * DRM_SCANOUTPOS_ACCURATE = Returned position is accurate. A lack of
  * this flag means that returned position may be offset by a constant but