Laptops with AMD APU doesn't restore display backlight brightness after
system resume.

This issue started when DC was introduced.

Let's use BL_CORE_SUSPENDRESUME so the backlight core calls
update_status callback after system resume to restore the backlight
level.

Tested on Dell Inspiron 3180 (Stoney Ridge) and Dell Latitude 5495
(Raven Ridge).
Signed-off-by: NKai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>