clat: split read_packet in twain am: e6e0c009b9

Original change: https://android-review.googlesource.com/c/platform/external/android-clat/+/2394652

Change-Id: I47d89b63f413ca7efb477b2de59af4f6070fb906
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>