etnaviv: fix 3d texture upload

etnaviv: fix 3d texture upload

Fix uploading of 3D textures and 2D array textures:

* Remove asserts in BLT and RS checking z
* Use box->z/box->depth in etna_copy_resource_box and CPU tile/untile
* Track mip level depth and use it in etna_copy_resource

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>