drm/radeon/r600_dma: Move 'r600_gpu_check_soft_reset()'s prototype to shared location

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/radeon/r600.c:1615:5: warning: no previous prototype for ‘r600_gpu_check_soft_reset’ [-Wmissing-prototypes]
 1615 | u32 r600_gpu_check_soft_reset(struct radeon_device *rdev)
 | ^~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/r600.c

@@ -39,6 +39,7 @@
 
 #include "atom.h"
 #include "avivod.h"
+#include "r600.h"
 #include "r600d.h"
 #include "rv770.h"
 #include "radeon.h"

drivers/gpu/drm/radeon/r600.h

+/* r600.h -- Private header for radeon driver -*- linux-c -*-
+ *
+ * Copyright 2008 Advanced Micro Devices, Inc.
+ * Copyright 2008 Red Hat Inc.
+ * Copyright 2009 Jerome Glisse.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __R600_H__
+#define __R600_H__
+
+struct radeon_device;
+
+u32 r600_gpu_check_soft_reset(struct radeon_device *rdev);
+
+#endif				/* __R600_H__ */

drivers/gpu/drm/radeon/r600_dma.c

@@ -24,10 +24,9 @@
 
 #include "radeon.h"
 #include "radeon_asic.h"
+#include "r600.h"
 #include "r600d.h"
 
-u32 r600_gpu_check_soft_reset(struct radeon_device *rdev);
-
 /*
  * DMA
  * Starting with R600, the GPU has an asynchronous