gpu/drm/radeon: fix spelling typo in comments

Modify the comment typo: "definately" -> "definitely".
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_vm.c

@@ -188,7 +188,7 @@ struct radeon_fence *radeon_vm_grab_id(struct radeon_device *rdev,
 	    vm_id->last_id_use == rdev->vm_manager.active[vm_id->id])
 		return NULL;
 
-	/* we definately need to flush */
+	/* we definitely need to flush */
 	vm_id->pd_gpu_addr = ~0ll;
 
 	/* skip over VMID 0, since it is the system VM */