scsi: aic7xxx: Remove unused variable 'targ'

Looks like checking the 'targ' was removed in 2005.

Fixes the following W=1 kernel build warning(s):

 drivers/scsi/aic7xxx/aic7xxx_osm.c: In function ‘ahc_send_async’:
 drivers/scsi/aic7xxx/aic7xxx_osm.c:1604:28: warning: variable ‘targ’ set but not used [-Wunused-but-set-variable]
 1604 | struct ahc_linux_target *targ;
 | ^~~~

Link: https://lore.kernel.org/r/20200713074645.126138-21-lee.jones@linaro.org
Cc: Hannes Reinecke <hare@suse.com>
Cc: "Daniel M. Eischen" <deischen@iworks.InterWorks.org>
Cc: Doug Ledford <dledford@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aic7xxx/aic7xxx_osm.c

@@ -1592,7 +1592,6 @@ ahc_send_async(struct ahc_softc *ahc, char channel,
 	case AC_TRANSFER_NEG:
 	{
 		struct	scsi_target *starget;
-		struct	ahc_linux_target *targ;
 		struct	ahc_initiator_tinfo *tinfo;
 		struct	ahc_tmode_tstate *tstate;
 		int	target_offset;
@@ -1626,7 +1625,6 @@ ahc_send_async(struct ahc_softc *ahc, char channel,
 		starget = ahc->platform_data->starget[target_offset];
 		if (starget == NULL)
 			break;
-		targ = scsi_transport_target_data(starget);
 
 		target_ppr_options =
 			(spi_dt(starget) ? MSG_EXT_PPR_DT_REQ : 0)