Revert "[media-plugins/gst-plugins-vaapi] add ~x86 keyword"

This reverts commit 9520ef6657f395f773e45da9a58930250dce654d.
Revert "[media-plugins/gst-plugins-vaapi] new ebuild, thanks to gentoo-zh overlay"

This reverts commit 240e1d45949683950747fa02a746e2e36c24222f.