[SCSI] qla2xxx: Avoid redundant RISC reset during (re)-initialization.

ISP24xx and above ISPs perform a RISC reset in
qla24xx_reset_chip(), which is called prior to
qla24xx_chip_diag().

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