egl/x11: resolve "initialization from incompatible pointer type" warning

egl/x11: resolve "initialization from incompatible pointer type" warning

With earlier commit we've moved a few functions and changing the
argument type from _EGLDisplay * to struct dri2_egl_display *.

The latter is effectively a wrapper around the former, thus
functionality was preserved, although GCC rightfully warned us about the
misuse.

Add a simple wrapper that casts and propagates the correct type.

Fixes: 9bbf3737f9c ("egl/x11: authenticate before doing chipset id
ioctls")
Cc: "11.2 11.1" <mesa-stable@lists.freedesktop.org>
Reported-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>