[SCSI] qla2xxx: Add midlayer target/device reset support.

Now that infrastructure is present within the midlayer and there
is a clear distinction between what is expected from a device and
target reset, convert the current device-reset codes to a
target-reset, and add codes to perform a proper device-reset (LUN
reset).

In the process of adding reset support, collapse and consolidate
large sections of mailbox-command (TMF issuance) codes,
generalize the two 'wait-for-commands-to-complete' functions, and
add a generic-reset routine for use by midlayer reset functions.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>