Partial revert of "IOMX: work against metadata buffer spoofing"

This reverts a change introduced in
6526ab6d that implements input port
rejection

- input port rejection breaks screen mirroring to Chromecast
- introduced with CM patch (https://review.lineageos.org/62373/

)
  "IOMX: work against metadata buffer spoofing"
- The CM patch should implement CVE-2016-6720 A-29422020, however, ASB
  patch does not change IOMX.cpp at all

Change-Id: I7890feb0786ce5d23edabacc4437902c9edb397d
Signed-off-by: WolfEnders <grzwolf1@gmail.com>