Camera: memcpy Blob header rather than directly writing fields

The CameraBlob embedded in the output bitstream may not be word aligned.
Directly casting a byte* to a CameraBlob and assigning its field could
cause alignment exception.

Use memcpy from a CameraBlob struct instead.

Test: Partner tested on 32-bit system
Bug: 260045056
Change-Id: I34b6ba8ded458b2dc59638a50237b7a1f64bfb86