Don't call setFrameRate if refresh rate switching is disabled

When refresh rate switching is set to SWITCHING_TYPE_NONE, DisplayManager
limits the refresh rate to a single value. Calling setFrameRate to SF
is redundant and causes unnecessary duplicate events.

Bug: 189174620
Bug: 189191861
Test: atest SetFrameRateTest
Test: atest FrameRateOverrideHostTest
Test: atest ChoreographerNativeTest
Test: atest FrameRateSelectionPriorityTests
Change-Id: I77ca430555c57c13a6e36707b344537deee5c2d7