drm/i915/dkl: return if tc_port is invalid in dkl_phy_set_hip_idx()

drm/i915/dkl: return if tc_port is invalid in dkl_phy_set_hip_idx()

In dkl_phy_set_hip_idx(), we may try to shift a value negatively,
whose behavior is undefined.  This can happen because we define
TC_PORT_NONE to -1, so theoretically tc_port could be -1.  We will
then use tc_port to shift to the correct address of the specified
port, but if it's negative, anything can happen.

If this happens or tc_port exceeds I915_MAX_TC_PORTS, it's safer to
return with a warning than risk an invalid write.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Link: https://lore.kernel.org/r/20250520082917.1302665-2-luciano.coelho@intel.com