irq handler in DRM(irq_install). Modify all drivers to ensure irq
handler is removed before cleanup and cleanup is called at takedown.
Remove unused buffer private struct fields in i810, i830. Check for
lock on init/cleanup in all drivers except i810/i830. The current DDX
for i810 and i830 doesn't hold the lock on kernel init (FIXME?).
Leif Delgass
Keith Whitwell
Jens Owen
Eric Anholt
Alan Hourihane