svga: don't advertise support for R32G32B32_UINT/SINT surface formats

svga: don't advertise support for R32G32B32_UINT/SINT surface formats

We want to be able to copy between different 32-bit, 3-channel surface
formats for GL_ARB_copy_image but since we don't support R32G32B32_FLOAT
for textures (it's not blendable and wouldn't work for render to texture)
we can't support 32-bit, 3-channel integer formats.

The state tracker will choose 4-channel formats instead.

Fixes the piglit arb_copy_image-format test for several cases.

Note: This change may need to be revisited if/when the texture_view exension
is enabled in driver.

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