cfg: drop CONFIG_DRM_KMS_FB_HELPER

   commit 91185d55b32e7e377f15fb46a62b216f8d3038d4
   Author: Thomas Zimmermann <tzimmermann@suse.de>
   Date:   Thu Apr 15 13:00:40 2021 +0200

       drm: Remove DRM_KMS_FB_HELPER Kconfig option

       It's only used by DRM_FBDEV_EMULATION, so inline it there.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
       Link: https://patchwork.freedesktop.org/patch/msgid/20210415110040.23525-5-tzimmermann@suse.de



Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>