Hold mfi_io_lock across calls to xpt_rescan() and xpt_alloc_ccb_nowait(). xpt_rescan() expects the SIM lock to be held, and we trip a mtx_assert if the driver initiates multiple rescans in quick succession.
Hold mfi_io_lock across calls to xpt_rescan() and xpt_alloc_ccb_nowait().
xpt_rescan() expects the SIM lock to be held, and we trip a mtx_assert if
the driver initiates multiple rescans in quick succession.

Reported by:	sbruno
Tested by:	sbruno
MFC after:	1 week

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