drm/i915/lt_phy: Add .disable_clock hook on DDI

drm/i915/lt_phy: Add .disable_clock hook on DDI

Add new pll_disable_clock functions so that they can be
hooked up to dpll->disable. This is just a wrapper over
the exitisting intel_xe3plpd_pll_disable to make it
compatible With dpll->disable function

v2: Revise commit message (Suraj)
    Drop wrapper for TBT clock disabling and reuse
    intel_mtl_pll_disable_clock() for DDI clock
    disabling hook (Suraj)

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260312080657.2648265-18-mika.kahola@intel.com