r600g/compute: Don't initialize vertex_buffer_state masks to 0x2
cs_vertex_buffer_state.enabled_mask and cs_vertex_buffer_state.dirty_mask are both updated when r600_set_constant_buffer() is called, so we don't need to manually update these values. This fixes a crash with OpenCL programs that have a kernel with no arguments. https://bugs.freedesktop.org/show_bug.cgi?id=82671 CC: "10.2" <mesa-stable@lists.freedesktop.org>