nvc0: enable compute shaders on GK104 and GM107+

Compute support on GK110 is still unstable for weird reasons, but
this can be fixed later as the NVF0_COMPUTE envvar prevent using
compute.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>

src/gallium/drivers/nouveau/nvc0/nvc0_screen.c

@@ -291,7 +291,8 @@ nvc0_screen_get_shader_param(struct pipe_screen *pscreen, unsigned shader,
    case PIPE_SHADER_CAP_PREFERRED_IR:
       return PIPE_SHADER_IR_TGSI;
    case PIPE_SHADER_CAP_SUPPORTED_IRS:
-      if (class_3d >= NVE4_3D_CLASS)
+      if (class_3d == NVF0_3D_CLASS &&
+          !debug_get_bool_option("NVF0_COMPUTE", false))
          return 0;
       return 1 << PIPE_SHADER_IR_TGSI;
    case PIPE_SHADER_CAP_MAX_INSTRUCTIONS: