drm/amdgpu/powerplay: include asm/div64.h for do_div()

BugLink: http://bugs.launchpad.net/bugs/1546572

Fixes: 1e4854e9 ("drm/amdgpu/powerplay: implement thermal control for tonga.")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit 8a0d560f)
Signed-off-by: Alberto Milone <alberto.milone@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/gpu/drm/amd/powerplay/hwmgr/fiji_thermal.c

@@ -20,7 +20,7 @@
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  */
-
+#include <asm/div64.h>
 #include "fiji_thermal.h"
 #include "fiji_hwmgr.h"
 #include "fiji_smumgr.h"

drivers/gpu/drm/amd/powerplay/hwmgr/tonga_thermal.c

@@ -20,7 +20,7 @@
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  */
-
+#include <asm/div64.h>
 #include "tonga_thermal.h"
 #include "tonga_hwmgr.h"
 #include "tonga_smumgr.h"