scsi: aic7xxx: remove set but not used variable 'shared_scb_data'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/aic7xxx/aic79xx_pci.c: In function 'ahd_pci_config':
drivers/scsi/aic7xxx/aic79xx_pci.c:291:19: warning:
 variable 'shared_scb_data' set but not used [-Wunused-but-set-variable]
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aic7xxx/aic79xx_pci.c

@@ -288,13 +288,11 @@ ahd_find_pci_device(ahd_dev_softc_t pci)
 int
 ahd_pci_config(struct ahd_softc *ahd, const struct ahd_pci_identity *entry)
 {
-	struct scb_data *shared_scb_data;
 	u_int		 command;
 	uint32_t	 devconfig;
 	uint16_t	 subvendor; 
 	int		 error;
 
-	shared_scb_data = NULL;
 	ahd->description = entry->name;
 	/*
 	 * Record if this is an HP board.