YubiKey: Retry to recover hotplugging

* Attempt one retry in the event the event the device was removed and
  re-inserted.

Signed-off-by: Kyle Manna <kyle@kylemanna.com>
YubiKey: Whitespace clean-up

* This was bugging me.  Oops.
* No functional changes.

Signed-off-by: Kyle Manna <kyle@kylemanna.com>