drm/kmb: Enable support for framebuffer console

Enable support for fbcon (framebuffer console).

v2: added missing static clk_enable
v3: removed module parameter, use fbdev_emulation instead. Use
preferred depth of 24 for color depth. (Thomas Z.)

Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211019230719.789958-2-anitha.chrisanthus@intel.com