lpdump: Automatically read from super when used directly on devices.

It's confusing to figure out how to invoke lpdump, especially on
retrofit devices. It should just do the correct thing automatically
when no arguments are passed.

Bug: N/A
Test: lpdump on retrofit device
Change-Id: I0563c10ff276763710fa0a4fb9918a2515f9d054
2 files changed