openharmony-standard: Simplified version of drmWaitVBlank hack

This simplifies and improves the hack added to libdrm to handle drivers (like
virtio drm) that does not support DRM_IOCTL_WAIT_VBLANK, and tries to return at
60 Hz points in time.

Signed-off-by: Esben Haabendal <esben@geanix.com>