• Remove redundant assertions that the driver lock is not held in attach() and detach() since mtx_lock() will assert that already since the driver lock is not recursive.
• Move the call to callout_init_mtx() before hme_stop() so that the callout_stop() in hme_stop() doesn't operate on an uninitialized callout structure during attach.

Reported by: yongari (2)
MFC after: 3 days