The perfect solution for psr_exit is the hardware tracking the changes and
doing the psr exit by itself. This scenario works for HSW and BDW with some
environments like Gnome and Wayland.

However there are many other scenarios that this isn't true. Mainly one right
now is KDE users on HSW and BDW with PSR on. User would miss many screen
updates. For instances any key typed could be seen only when mouse cursor is
moved. So this patch introduces the ability of trigger PSR exit on kernel side
on some common cases that.

Most of the cases are coverred by psr_exit at set_domain. The remaining cases
are coverred by triggering it at set_domain, busy_ioctl, sw_finish and
mark_busy.

The downside here might be reducing the residency time on the cases this
already work very wall like Gnome environment. But so far let's get focused
on fixinge issues sio PSR couild be used for everybody and we could even
get it enabled by default. Later we can add some alternatives to choose the
level of PSR efficiency over boot flag of even over crtc property.

v2: remove exit from connector_dpms. Daniel pointed this is the wrong way and
also this isn't needed for BDW and HSW anyway.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Vijay Purushothaman <vijay.a.purushothaman@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>