[SCSI] qla2xxx: Consolidate ISP24xx chip reset logic.

Consolidate ISP24xx chip reset logic.

Consolidate near-duplicate RISC reset logic from
qla24xx_reset_chip() and qla24xx_chip_diag().  Also, after
initiating a soft-reset, insure the firmware has completed
all NVRAM accesses before continuing.

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