drm/i915: Move shared DPLL disabling into CRTC disable hook

The spec requires disabling the PLL on TC ports before disconnecting the
port's PHY. Prepare for that by moving the PLL disabling to the CRTC
disable hook, while disconnecting the PHY will be moved to the
post_pll_disable() encoder hook in the next patch.

v2: Move the call from intel_crtc_disable_noatomic() as well.

Reviewed-by: Mika Kahola <mika.kahola@intel.com> # v1
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323142035.1432621-27-imre.deak@intel.com