SF: Handle the empty hdr10plus metadata in setPerFrameMetadata

There was a case that Media enabled HDR10PLUS in validTypes without
passing any metadata.The patch handles the error to avoid the crash of
SurfaceFlinger.

Bug: 157868992
Test: atest android.mediav2.cts.CodecDecoderSurfaceTest
Change-Id: I57275672ef2fe8079e652094e77a0a50de10c5b9
2 files changed