drm/amdgpu: init atpx at switcheroo register time (v2)

If we do it at enable time, it's too late for the feature
checks.

v2: drop .init setting as per Peter's comments

Reviewed-by: Peter Wu <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
Cc: Peter Wu <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c

···
 static const struct vga_switcheroo_handler amdgpu_atpx_handler = {
 	.switchto = amdgpu_atpx_switchto,
 	.power_state = amdgpu_atpx_power_state,
-	.init = amdgpu_atpx_init,
 	.get_client_id = amdgpu_atpx_get_client_id,
 };
 
···
 		printk(KERN_INFO "vga_switcheroo: detected switching method %s handle\n",
 		       acpi_method_name);
 		amdgpu_atpx_priv.atpx_detected = true;
+		amdgpu_atpx_init();
 		return true;
 	}
 	return false;