[SCSI] advansys: Fix simultaneous calls to ->queuecommand

The narrow board used two global structures to set up a command;
unfortunately they weren't locked, so with two boards in the machine,
one call to queuecommand could corrupt the data being used by the other
call to queuecommand.

Fix this by allocating asc_scsi_q on the stack (64 bytes) and using kmalloc
for the asc_sg_head (2k)

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>