drm/amdgpu: remove AMDGPU_VM_NO_FLUSH define

Not used any more.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NEdward O'Callaghan <funfunctor@folklore1984.net>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -51,9 +51,6 @@
  * SI supports 16.
  */
 
-/* Special value that no flush is necessary */
-#define AMDGPU_VM_NO_FLUSH (~0ll)
-
 /* Local structure. Encapsulate some VM table update parameters to reduce
  * the number of function parameters
  */