Add toString() to Display.HDRCapabilities

HdrCapablities in adb shell dumpsys display and in log messages appear
as android.view.Display$HdrCapabilities@49f9cd26. This change adds a
toString() method so HDR Capabilities are visualized in a nice way.

Test: adb shell dumpsys display
Change-Id: I0800ac4f615ca733d0901654184d884dd2b81752
1 file changed