drm/radeon/radeon_device: remove unused function

We get 2 warnings when building kernel with W=1:
drivers/gpu/drm/radeon/radeon_device.c:1961:5: warning: no previous prototype for 'radeon_debugfs_init' [-Wmissing-prototypes]
drivers/gpu/drm/radeon/radeon_device.c:1966:6: warning: no previous prototype for 'radeon_debugfs_cleanup' [-Wmissing-prototypes]

In fact, these functions are dummy, but can be removed,
so this patch removes them.

Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Baoyou Xie <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/radeon_device.c

···
 	}
 #endif
 }
-
-#if defined(CONFIG_DEBUG_FS)
-int radeon_debugfs_init(struct drm_minor *minor)
-{
-	return 0;
-}
-
-void radeon_debugfs_cleanup(struct drm_minor *minor)
-{
-}
-#endif

drivers/gpu/drm/radeon/radeon_drv.c

···
 extern long radeon_kms_compat_ioctl(struct file *filp, unsigned int cmd,
 				    unsigned long arg);
 
-#if defined(CONFIG_DEBUG_FS)
-int radeon_debugfs_init(struct drm_minor *minor);
-void radeon_debugfs_cleanup(struct drm_minor *minor);
-#endif
-
 /* atpx handler */
 #if defined(CONFIG_VGA_SWITCHEROO)
 void radeon_register_atpx_handler(void);
···
 	.disable_vblank = radeon_disable_vblank_kms,
 	.get_vblank_timestamp = radeon_get_vblank_timestamp_kms,
 	.get_scanout_position = radeon_get_crtc_scanoutpos,
-#if defined(CONFIG_DEBUG_FS)
-	.debugfs_init = radeon_debugfs_init,
-	.debugfs_cleanup = radeon_debugfs_cleanup,
-#endif
 	.irq_preinstall = radeon_driver_irq_preinstall_kms,
 	.irq_postinstall = radeon_driver_irq_postinstall_kms,
 	.irq_uninstall = radeon_driver_irq_uninstall_kms,