drm/encoder: Don't raise voice in drm_encoder_mask() documentation

There's no need to raise our voice when saying encoder, we're all
civilized adults here!
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190913222704.8241-4-lyude@redhat.comReviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

include/drm/drm_encoder.h

@@ -198,7 +198,7 @@ static inline unsigned int drm_encoder_index(const struct drm_encoder *encoder)
 }
 
 /**
- * drm_encoder_mask - find the mask of a registered ENCODER
+ * drm_encoder_mask - find the mask of a registered encoder
  * @encoder: encoder to find mask for
  *
  * Given a registered encoder, return the mask bit of that encoder for an