mfi(4): Don't assert lock holding when dumping or during a panic.
FreeBSD's mtx_assert() does it the same way, but we usually translate
mtx_assert() into a KKASSERT(lockstatus(&lock, curthread) != 0).
For now, replace all of these assertions in mfi(4) with a function that
mimics the mtx_assert() behavior of FreeBSD, since some of the asserting
functions are used by the dumping code.
We might think about a real lockassert() function in the future that
has this exception too.
This commit fixes dumping on most supported adapters. Thunderbolt series
adapters still have an (unrelated) command timeout issue which I'm
Reported and tested (on a PERC 5/i) by Tim Howe <firstname.lastname@example.org>.