[SCSI] qla2xxx: Add Flash-Access-Control support for recent ISPs.

Given the low-level interface varies from one flash-part
manufacturer to the next, the Flash-Access-Control (FAC) mailbox
command makes the specific flash type transparent to the driver
by encapsulating a basic set of accessor and update routines.
Use these new routines where applicable by querying FAC opcode
get-sector-size at init-time.

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