drm/i915: Sanitize the TypeC FIA lane configuration decoding

Use hex numbers, since that makes more sense when decoding a bit pattern.

No functional change.

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Animesh Manna <animesh.manna@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190628143635.22066-16-imre.deak@intel.com