SurfaceFlinger: treat the desiredRefreshRate of ExplicitDefault as max

When a an app calls to
ANativeWindow_setFrameRate(..., ANATIVEWINDOW_FRAME_RATE_COMPATIBILITY_DEFAULT)
it usually uses the frame render time to calculate the desired refresh rate.
Change the platform side algorithm to consider the desired refresh rate in
that case to the highest frame production rate.

Test: adb shell /data/nativetest64/libsurfaceflinger_unittest/libsurfaceflinger_unittest
Bug: 147516364
Bug: 150977265
Change-Id: Icda006de0aeb22da8244baee936947495f813e1b