svga: avoid try_blit() for some depth formats on non vgpu10.

svga: avoid try_blit() for some depth formats on non vgpu10.

On non vgpu10, driver doesn't support util_blitter_blit for SVGA3D_Z_D16,
SVGA3D_Z_D24x8, SVGA3D_Z_D24S8. Patch fixes following piglit tests regression on hwv8 caused
by commit 27bf35caea5e:
spec@arb_depth_texture@fbo-depth-gl-depth-component16-blit
spec@arb_depth_texture@fbo-depth-gl-depth-component24-blit
spec@arb_depth_texture@fbo-depth-gl-depth-component32-blit

Tested with mtt-piglit on hw 8,9,10,11,13 and mtt-glretrace on windows and linux.

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