Vulkan: only report refreshDuration, not {min|max}RefreshDuration

Test: Manually tested with a modified cube demo, that reports the refresh
duration returned from this extension.

As part of discussions within Khronos, it was decided that
VK_GOOGLE_display_timing should only report one refresh duration for a display,
and assume that it's refresh rate is fixed (which is the case for our current
devices).

Change-Id: I772348281c18a36b02dcfe0519d1943e25a41f7c
diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index 4be11b4..750e653 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -150,9 +150,7 @@
             nsecs_t* outLastRefreshStartTime, nsecs_t* outGlCompositionDoneTime,
             nsecs_t* outDisplayPresentTime, nsecs_t* outDisplayRetireTime,
             nsecs_t* outDequeueReadyTime, nsecs_t* outReleaseTime);
-
-    status_t getDisplayRefreshCyclePeriod(nsecs_t* outMinRefreshDuration,
-            nsecs_t* outMaxRefreshDuration);
+    status_t getDisplayRefreshCycleDuration(nsecs_t* outRefreshDuration);
 
     status_t getUniqueId(uint64_t* outId) const;
 
@@ -210,7 +208,7 @@
     int dispatchSetAutoRefresh(va_list args);
     int dispatchEnableFrameTimestamps(va_list args);
     int dispatchGetFrameTimestamps(va_list args);
-    int dispatchGetDisplayRefreshCyclePeriod(va_list args);
+    int dispatchGetDisplayRefreshCycleDuration(va_list args);
 
 protected:
     virtual int dequeueBuffer(ANativeWindowBuffer** buffer, int* fenceFd);