drm/i915/tc: un-inline intel_tc_port_ref_held()

Avoid including the intel_drv.h mega header from other header files to
make further header cleanup easier.

v2: restore the over-eagerly dropped <linux/types.h> (Imre)

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190806113700.18816-1-jani.nikula@intel.com