Fix the argument processing when dumping Bluetooth state

Apparently, when dump() is invoked via bugreport for
Bluetooth's AdapterServe, the optional arguments contain "-a".
The existing logic for checking the arguments for "--proto"
and return the result in Protobuf format failed to detect that,
and suppressed any output.

Now any unrecognized options are ignored, and the default
(text) output is returned.

Bug: 27293885
Change-Id: I0f0d94507ebf6fed7628d49cd1de2a1b2801e6ad