i965: Make intel_miptree_prepare_texture() take level/layer arguments.

i965: Make intel_miptree_prepare_texture() take level/layer arguments.

This effectively exports intel_miptree_prepare_texture_slices() as
intel_miptree_prepare_texture().  The hope is to avoid resolves for
when using texture views that access a subset of the levels/layers.

For now, we pass the same arguments to separate the mechanical change
from the one that actually modifies our behavior.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by; Jason Ekstrand <jason@jlekstrand.net>