drm/i915/tc: Rename tc_phy_status_complete() to tc_phy_is_ready()

For consistency rename tc_phy_status_complete() to tc_phy_is_ready()
following the terminology of new platforms.

Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323142035.1432621-4-imre.deak@intel.com