lima: implement zsbuf reload
Fragment shader can write depth and stencil if we set necessary flags in RSW. In addition to that we need to use special format for Z24S8. Original format is apparently Z24X8 since we can't sample stencil in GLES2.
This MR also disables Z16 format since we don't know how to reload Z16 buffers yet. Blob seems to use Z24 in dEQP tests that need depth reload, e.g.:
Edited by Vasily Khoruzhick