VTS: Validate that getDisplayIdentificationData returns EDID

Accroding to the documentation getDisplayIdentificationData
"data is the EDID 1.3 blob identifying the display".

This CL runs a basic validation that the returned data is
an EDID.

Test: atest VtsHalGraphicsComposerV2_3TargetTest
Bug: 191851265
Change-Id: I7604f3dc68095612d79bb04243918d6348de6c89