[SCSI] mpt fusion: lock down ScsiLookup

ScsiLookup is an array of pending scmd pointers that the scsi lld
maintains. This array is touched from queuecommand, eh threads, and
interrupt context. This array should put under locks, hence this patch
to synchronize its access.  I've added some nice little function
wrappers for this, and moved the ScsiLookup array over to MPT_ADAPTER
struct.

Signed-off-by: Eric Moore <Eric.Moore@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>