drm/i915/lt_phy: Enable dpll framework for xe3plpd

drm/i915/lt_phy: Enable dpll framework for xe3plpd

xe3plpd platform is supported by dpll framework remove a separate
check for hw comparison and rely solely on dpll framework
hw comparison.

Finally, all required hooks are now in place so initialize
PLL manager for xe3plpd platform and remove the redirections
to the legacy code paths for clock enable/disable as well as
state mismatch checks that are no longer needed.

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260312101415.2669387-1-mika.kahola@intel.com