drm/amdgpu: allow passing absolute timeouts to amdgpu_cs_query_fence_status

Useful when Mesa wants to wait for a lot of fences at the same time and
doesn't want to recalculate the relative timeout after every call.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/amdgpu/amdgpu.h b/amdgpu/amdgpu.h
index daeebbe..9d16430 100644
--- a/amdgpu/amdgpu.h
+++ b/amdgpu/amdgpu.h
@@ -52,10 +52,15 @@
 #define AMDGPU_CS_MAX_IBS_PER_SUBMIT		4
 
 /**
- *
+ * Special timeout value meaning that the timeout is infinite.
  */
 #define AMDGPU_TIMEOUT_INFINITE			0xffffffffffffffffull
 
+/**
+ * Used in amdgpu_cs_query_fence::flags, meaning that the given timeout
+ * is absolute.
+ */
+#define AMDGPU_QUERY_FENCE_TIMEOUT_IS_ABSOLUTE     (1 << 0)
 
 /*--------------------------------------------------------------------------*/
 /* ----------------------------- Enums ------------------------------------ */