radeonsi: don't update dependent states if it has no effect (v2)

radeonsi: don't update dependent states if it has no effect (v2)

This and the previous clip_regs commit decrease IB sizes and the number of
si_update_shaders invocations as follows:

                 IB size   si_update_shaders calls
Borderlands 2      -10%            -27%
Deus Ex: MD         -5%            -11%
Talos Principle     -8%            -30%

v2: always dirty cb_render_state in set_framebuffer_state

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>