Check target duration sent instead of exact value

Flinger commit start is undeterministic since test calling
commitAndComposite and thus making the test flaky.

Bug: b/204322192
Test: atest libsurfaceflinger_unittest:libsurfaceflinger_unittest.SurfaceFlingerPowerHintTest
Change-Id: I67cccbc87167d27a5fdead915a20aeed1f764e19
1 file changed