vaapisink: White is rendered pink with AMD card, wrong hue everywhere in RGBA and BGRA formats

Submitted by Alicia Boya García @ntrrgc

Link to original bug (#793886)

Description

Testcase:

$ gst-launch-1.0 multifilesrc location="frame_01.png" caps="image/png,framerate=(fraction)3/1" ! pngdec ! videoconvert ! vaapisink

Works fine with xvimagesink:

$ gst-launch-1.0 multifilesrc location="frame_01.png" caps="image/png,framerate=(fraction)3/1" ! pngdec ! videoconvert ! xvimagesink