drm/i915/hdmi: fix vlv infoframe port check

Due to missing shifting, the vlv infoframe port check only works for
port A. Fix it. Broken since introduction in

commit 535afa2e
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Wed Apr 15 16:52:29 2015 -0700

    drm/i915/vlv: check port in infoframe_enabled v2

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90059


Tested-by: xubin <bin.a.xu@intel.com>
Tested-by: Ye Tian <yex.tian@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>