Revert "i965: Restore vbo after color resolve during brw_try_draw_prims()"

Revert "i965: Restore vbo after color resolve during brw_try_draw_prims()"

This got pushed accidentally in the first place but wasn't reverted
as it didn't regress piglit but instead fixed one newly introduced
test exercising a corner in case in i965 driver. However, saving and
restoring vertex buffer context is complicated and requires more
thought.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94150

Signed-off-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by: Tapani Palli <tapani.palli@intel.com>