a3xx: rename texture/vertex formats to a more unified scheme
a3xx: add a few snorm rb formats

Determined through experimentation
a3xx: add 16-bit unorm/snorm texture formats
a4xx: stencil/depth fixes

RB_DEPTH_PITCH actually takes a stride (pitch * cpp), as on a3xx.  Also
add texture format value for NORM_UINT_8_8 used for z16 restore.