drm/i915: Call intel_pre_plane_updates() also for pipes getting enabled

We used to call intel_pre_plane_updates() for any pipe going through
a modeset whether the pipe was previously enabled or not. This in
fact needed to apply all the necessary clock gating workarounds/etc.
Restore the correct behaviour.

Fixes: 39919997

 ("drm/i915: Disable all planes before modesetting any pipes")
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231121054324.9988-3-ville.syrjala@linux.intel.com
(cherry picked from commit e0d5ce11

)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>