MFH: r489829

graphics/drm-legacy-kmod: Update snapshot

Update graphics/drm-legacy-kmod to the latest snapshot, which includes
FreeBSD base r342888 by markj:

Complete the removal of obsolete ioctl handlers.

This is a followup to the previous update, and base r342182.

Approved by: jmd (maintainer, implicit)

Approved by: ports-secteam (blanked, drm drivers)