Currently libdrm_amdgpu provides a typedef of the various handles. While
the goal was to make those opaque, it effectively became part of the API

To the best of my knowledge there are two ways to have opaque handles:
 - "typedef void *foo;" - rather messy IMHO
 - "stuct foo;" and use "struct foo *" through the API

In our case amdgpu_device_handle is used only internally, plus
respective code is not used or applicable for r300 and r600. Hence we
copied the typedef.

Seemingly this will be a problem since libdrm_amdgpu wants to change the
API, while not updating the code(?).

Either way, we can safely s/amdgpU_device_handle/void */ and carry on.

Cc: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak at amd.com>