We're going to want access to the atomic state for iterating
the slave crtcs when enabling the port sync master crtc. Pass
the atomic state all the way down.

The alternative would be yet another encoder hook which we'll
have to call after all the normal modeset stuff is done. Not
really a fan of yet another hook just for this.

Note that during readout state sanitation we are now going
to pass NULL as the atomic state since we don't have one.
We need to change that and then we can also s/crtc_state/crtc/
and s/conn_state/conn/ for the encoder hooks as well.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-13-ville.syrjala@linux.intel.comReviewed-by: José Roberto de Souza <jose.souza@intel.com>