drm/i915: Move intel_disable_shared_dpll() into ilk_pch_post_disable()

drm/i915: Move intel_disable_shared_dpll() into ilk_pch_post_disable()

On ILK-IVB only PCH outputs use shared dplls. Move the relevant
intel_disable_shared_dpll() into ilk_pch_post_disable() to make
that clear (and if we extend the dpll mgr to cover all plls we need
different enable/disable points anyway for the PCH vs. CPU eDP cases).
The intel_enable_shared_dpll() counterpart was already in
ilk_pch_enable() anyway, so this is the more symmetric place for the
disable as well.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250310183528.3203-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>