fixup! Allow ota_from_target_file to work entirely on directories

The following log message would always be shown:
WARNING : Cannot find care map file in target_file package

Break out of the care map copying loop as soon a file has been
copied. This ensures that else statement is only executed if no
care map file exists.

Test: Manual. Run ota_from_target_files with target-zip with and
    without care map files.
Change-Id: Ia196aa182ed81f21424317a7005f5634866b4b99