bluetooth-config: Fix command line parsing

This addresses the problems encountered when parsing options in bluetooth-config.

• the optional parameters were not properly shifted after consumption
• the command line parameter count was checked before getopts and not after

Reported by: sjg
Approved by: kp
MFC after: 7 days
Event: Berlin Hackathon 202507
Differential Revision: https://reviews.freebsd.org/D51281

(cherry picked from commit 5031da20599bb1163f0e8d1c4b415ab3bbebce00)