[SCSI] qla2xxx: ensure flash operation and host reset via sg_reset are mutually exclusive

The problem occurring is a hw-race where there's an outstanding read-flash
operation occurring while the chip is being reset (done via an sg_reset script).
After the chip is paused, the read-flash operation never completes and the
DPC thread, while trying to complete the reset, is never able to recover,
as the HW appears to be hung...

The fix is to wait for outstanding flash operation prior to doing a sg_reset -h.
And to wait for reset to complete before any flash operations.

Note, during the wait, if any of the operation (reset/flash) does not complete,
failure is returned to the upper layer. The upper layer either need to
fail or retry.

Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>