svga: Use comparison between svga texture types to use PredCopyRegion command

svga: Use comparison between svga texture types to use PredCopyRegion command

PredCopyRegion support copy between same type of textures.
Instead of comparing src and dst pipe texture type, compare svga texture
type which can avoid some software fallback.
for example, it avoids a software blit with the Redway3D Aston demo.

Tested piglit tests on VGPU9 and  VGPU10 on GL/DX11Renderer, Redway3D Aston demo

v2: some nit pick suggested by Charmaine.

Reviewed-by: Charmaine Lee <charmainel@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>