drm/simple-kms-helper: Add mode_fixup() to simple display pipe The mode fix-up function for simple display helpers is equivalent to the regular pipeline's CRTC mode fix-up function. It's called to adjust the CRTC's display mode for the encoder. Add this function for DRM fbconv helpers. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>