Have vkGetRefreshCycleDurationGOOGLE query SF every time.

When VK_GOOGLE_display_timing was first created, we assumed displays
never changed refresh rates.  Now that they are dynamic, we need to
query SF everytime the app requests it.

Test: ANGLE-on-Vulkan
Bug: b/130888074
Change-Id: I5eb9a20690f82b8663899a2ded8b5bb866cebe58