gallium/targets/d3dadapter9: Fix device detection for render-nodes

gallium/targets/d3dadapter9: Fix device detection for render-nodes

When on a render node the unique ioctl doesn't work.

This patch drops the code to detect the device, which relied
on an ioctl, and replaces it by the mesa loader function.
The mesa loader function is more complete and won't fail for render-nodes.

Alternatively we could also have used the pipe cap to
determine the vendor and device id from the driver.

Reviewed-by: Tiziano Bacocco <tizbac2@gmail.com>
Signed-off-by: Axel Davy <axel.davy@ens.fr>