Clean up the GraphicBuffer.

HIDL tests don't have any buffer created when test execution starts and with GraphicBuffer that wasn't the case.
We only initialize the buffer when required the way gralloc implementation did.

BUG: 199413815

Test: atest VtsHalGraphicsComposer3_TargetTest
Change-Id: I3aeec5b00e30e636de2e58cf7e6ced5539ae19b6
3 files changed