[SCSI] qla2xxx: Collapse RISC-RAM retrieval code during a firmware-dump.

Use the more efficient read-DMA'ble-buffer mailbox commands
rather than reading a single word/dword at a time.  We also
remove a bulk of the duplicate mailbox command-handling codes in
favor of more generic read-memory() routines (qla2xxx_dump_ram()
and qla24xx_dump_ram()).

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