daemon: only call pw_log_set_level() if -v is actually given

Previous commit 69e935e8 unconditionally called pw_log_set_level() after
the option parsing. If pw_init() changed the logging level based on
PIPEWIRE_DEBUG, we'd now overwrite that change.

Call pw_log_set_level() only if -v is actually given on the commandline.
This means a commandline option will override PIPEWIRE_DEBUG if set but
that is intended.

Fixes 69e935e8