drm/i915/psr: Disable PSR before modesets turn off all planes

drm/i915/psr: Disable PSR before modesets turn off all planes

PSR2 apparently requires some planes to be enabled for some
silly reason, and so we are now trying to turn PSR off before
planes go off. Except during a full modeset that is handled
less clearly through reorganization of the modeset sequence.
That is not great as it makes the code mode complex, and
prevents us from doing nice things such as just turning off
all the planes at the very start of the modeset. So let's
move the PSR pre_plane_update() thing to a spot where it
will handle both full modesets and everything else.

Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211022103304.24164-2-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>