[SCSI] qla2xxx: Add flash burst-read/write support.

Newer ISPs support a mechanism to read and write flash-memory via
the firmware LOAD/DUMP memory mailbox command routines.  When
supported, utilizing these mechanisms significantly reduces
overall access times.

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