MFH: r519046

graphics/drm-fbsd11.2-kmod: Update snapshot

Update graphics/drm-fbsd11.2-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

Security: ecb7fdec-0b82-11ea-874d-0c9d925bbbc0

Approved by: ports-secteam (implicit, security, drm-drivers blanket)