In a charger mode manual test, we encounter failures from the
MinuiBackendDrm when calling DrmEnableCrtc and Flip. To make the minui
more robust, we should fall back to another backend if drm's SetCrtc
fails. And check the value of gr_draw before dereferencing.
Bug: 80249440
Test: boot to recovery
Change-Id: Ibd1ca1fb1115fe1132684586c54eccd8fb4c3ad9