Revert "gl: Use GstGLDisplayEGL directly instead of creating a GstGLDisplayVIVFb...

Revert "gl: Use GstGLDisplayEGL directly instead of creating a GstGLDisplayVIVFb subclass"

This reverts commit 47fd4d391e775c11f529705bb0f457a9d25ba5e7.

This patch is incorrect. It doesn't actually compile, and causes a crash
because the viv-fb window implementation needs a native EGL handle
to pass to fbCreateWindow, but the GstGLDisplayEGL handleis actually
an EGLDisplay now (and gets cast to the wrong type)