drm: EDID accept separate sync video mode

X is accepting such video mode, do the same. Pointed out by Joshua Roys
on IRC. Fix https://bugzilla.redhat.com/show_bug.cgi?id=540024

[fix printf to use composite not integrated :- airlied]
Signed-off-by: NJerome Glisse <jglisse@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_edid.c

@@ -633,8 +633,7 @@ static struct drm_display_mode *drm_mode_detailed(struct drm_device *dev,
 		return NULL;
 	}
 	if (!(pt->misc & DRM_EDID_PT_SEPARATE_SYNC)) {
-		printk(KERN_WARNING "integrated sync not supported\n");
-		return NULL;
+		printk(KERN_WARNING "composite sync not supported\n");
 	}
 
 	/* it is incorrect if hsync/vsync width is zero */