Turn on display before running tests

Some CTS media drm tests require the display
to turn on to pass, such as testClearKeyPlaybackCenc2.

This CL turns on display before running tests.

Testing methods:
- turn off display
- run testClearKeyPlaybackCenc2: test failed
- apply change
- display will turn on and test passed

Test: atest
  atest CtsMediaTestCases:android.media.cts.MediaDrmClearkeyTest#testClearKeyPlaybackCenc2

Bug: 185930906
Change-Id: Id8990012841138409ee00424a3cbd9bba801da2b