drm/i915: Nuke debug messages from the pipe update critical section

drm/i915: Nuke debug messages from the pipe update critical section

BugLink: http://bugs.launchpad.net/bugs/1685140
commit edd06b8353772dca7afcd4640dafa83b521edd55 upstream.

printks are slow so we should not be doing them from the vblank evade
critical section. These could explain why we sometimes seem to
blow past our 100 usec deadline.

The problem has been there ever since commit bfd16b2a23dc ("drm/i915:
Make updating pipe without modeset atomic.") but it may not have
been readily visible until commit e1edbd44e23b ("drm/i915: Complain
if we take too long under vblank evasion.") increased our chances
of noticing it.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: bfd16b2a23dc ("drm/i915: Make updating pipe without modeset atomic.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170307205419.19447-1-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
(cherry picked from commit c3f8ad57a01a31397e5a0349a226a32f35ddc19c)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>