graphics/drm-fbsd12.0-kmod: Update snapshot

Update graphics/drm-fbsd12.0-kmod to the latest snapshot. This is a security
update, containing fixes for local privilege escalation and denial of
service bugs, as part of the Intel 2019.2 IPU

MFH: 2019Q4 (implicit, security, drm-drivers blanket)
Security: ecb7fdec-0b82-11ea-874d-0c9d925bbbc0