With an AST2600, the screen is garbage when going out of suspend.
This is because color settings are lost, and not restored on resume.
Force the color settings on DPMS_ON, to make sure the settings are correct.

I didn't write this code, it comes from the out-of-tree aspeed driver v1.13
https://www.aspeedtech.com/support_driver/Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Venkat Tadikonda <venkateswara.rao@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220622124815.356035-1-jfalempe@redhat.com