net/usb/pegasus: avoid hundreds of diagnostics

Make the "pegasus" driver scream less loudly in the face of
problems as it initializes, avoiding hundreds of messages:

 - ratelimit some key error messages
 - avoid some spurious diagnostics caused by strange codeflow

And fix one instance of goofy indentation.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>