sf: change the mock method for callback APIs

Following the change in callback function, the patch changes the mock
methods in unit tests and also removes the requirement of calling
isSupported function since it is not necessary in all implementations.

Bug: 194068871
Test: atest libsurfaceflinger_unittest
Change-Id: I22dc25b4118878623871b4547c83f4ab51923985
3 files changed