drm/amdgpu: simplify gds_compute_max_wave_id computation

static void gfx_v10_0_set_gds_init(struct amdgpu_device *adev)

{

	/* init asic gds info */

	switch (adev->asic_type) {

	case CHIP_NAVI10:

	default:

		adev->gds.gds_size = 0x10000;

		adev->gds.gds_compute_max_wave_id = 0x4ff;

		break;

	}

	unsigned total_cu = adev->gfx.config.max_cu_per_sh *

			    adev->gfx.config.max_sh_per_se *

			    adev->gfx.config.max_shader_engines;

	adev->gds.gds_size = 0x10000;

	adev->gds.gds_compute_max_wave_id = total_cu * 32 - 1;

	adev->gds.gws_size = 64;

	adev->gds.oa_size = 16;

}