imx-vpu: bump version to 5.4.27

- imx-vpu version changed to internal version
- VPU share memory file open fixes
- Upgrade ion usage
- Remove obey-variables patch -now included in release

This patch is based on the Yocto equivalent:
https://github.com/Freescale/meta-fsl-arm/commit/db343da3e4eb2afa6a72f7526751bb8d8ba287e1

The IOGetVirtMem return value patch has now been included into the upstream
package.

This package has been implicitely tested through gstreamer as the plugins
rely on it for vpu decoding:
 # gst-launch-0.10 playbin uri=file:///root/tears_of_steel_1080p.webm
 # gst-launch-1.0 playbin uri=file:///root/tears_of_steel_1080p.webm


 # gst-launch-1.0 filesrc location=/root/tears_of_steel_1080p.webm ! \
   matroskademux ! imxvpudec ! imxipuvideosink

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>