i965: Switch TCS gl_program/gl_shader_program checks over to TES.

i965: Switch TCS gl_program/gl_shader_program checks over to TES.

Tessellation control shaders are optional, but evaluation shaders will
always be present when using tessellation.  However, we'll always enable
the TCS (HS) hardware stage when using tessellation - we'll just create
a program on the fly.

That program, however, won't have a gl_program or gl_shader_program.
So we shouldn't check brw->tess_ctrl_program or
shader_prog->_LinkedShaders[MESA_SHADER_TESS_CTRL] - if we want to know
whether tessellation is enabled, we should look for a TES.

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