For several reasons, I don't think it's particularly useful to have
separate flags:

1. Most of the time, tessellation shaders are paired, so both will be
   replaced at the same time.

2. The data layout is tightly coupled.  Both need to agree on the number
   of per-patch slots in the VUE map.  Even adding extra TCS outputs
   that aren't read by the TES will trigger the need for recompiles.

3. The TCS is optional from an API perspective, but required by the
   hardware whenever tessellation is enabled.  So, atoms that deal with
   the TCS must check brw->tess_eval_program (BRW_NEW_TESS_EVAL_PROGRAM?)
   rather than brw->tess_ctrl_program to tell whether tessellation is
   enabled.

So, not only is it unlikely to be useful, it's a bit confusing to get
right.  Simply using one flag for both simplifies this.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>