drm/i915: remove HAS_PCH_NOP() dependency from clock gating

drm/i915: remove HAS_PCH_NOP() dependency from clock gating

intel_pch_init_clock_gating() already handles unsupported PCH types,
including PCH_NOP, by doing nothing.

Drop the explicit HAS_PCH_NOP() check from the IVB clock gating
path and always call the display helper directly. This removes one
more direct dependency on display-side PCH macros from
intel_clock_gating.c.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patch.msgid.link/20260428095104.818360-9-luciano.coelho@intel.com
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>