isl: Validate row pitch of stencil surfaces.
Also, silence an obnoxious finishme that started occurring for all GL applications which use stencil after the i965 ISL conversion. v2: Check against 3DSTATE_STENCIL_BUFFER's pitch bits when using separate stencil, and 3DSTATE_DEPTH_BUFFER's bits when using combined depth-stencil. Cc: "17.2" <mesa-stable@lists.freedesktop.org> Reviewed-by:Jason Ekstrand <jason@jlekstrand.net> (cherry picked from commit 5563872d)