drm/i915/tc: Skip ref held check for TC legacy aux power wells

As part of ICL TC cold exit sequences we need to request aux power
well before lock the access to TC ports, so skiping the
intel_tc_port_ref_held() check for TC legacy ports.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Tested-by: You-Sheng Yang <vicamo.yang@canonical.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200414194956.164323-5-jose.souza@intel.com