MFC r327529: ath: fix possible memory disclosure in ioctl handler

Submitted by: Domagoj Stolfa <domagoj.stolfa@gmail.com>

MFC r283291: don't use CALLOUT_MPSAFE with callout_init()

The main purpose of this MFC is to reduce conflicts for other merges.
Parts of the original change have already "trickled down" via individual MFCs.

MFC r256658, r256666:

Move a lot of debugging printf's to DPRINTF.

MFC r256658, r256666:

Move a lot of debugging printf's to DPRINTF.