svga: adjust line subpixel position for HWv8

This fixes two regressions on HWv8:
  Piglit gl-1.0-ortho-pos
  Piglit/glean fbo
This was caused by commit c2b92dada076a "svga: clamp device line width
to at least 1 to fix HWv8 line stippling"

This also fixes two conform tests: Vertex Order and Polygon Face

No Piglit/conform changes with HWv9 or later.

VMware bug 1905053

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