drm/i915/tc: Fix PHY ownership programming in HDMI legacy mode

Make sure the TypeC PHY ownership flag is not getting reset during
an HDMI modeset on the given port. Besides the WARN this triggered, it
didn't cause other issues, since for TypeC legacy mode setting the
PHY ownership flag is optional (there is no other user of the PHY
besides display).

Reported-and-tested-by: Shawn C Lee <shawn.c.lee@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220726134313.1484763-1-imre.deak@intel.com