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>