scsi: gdth: Remove set but used 'cmd_index'

This addresses the following gcc warning with "make W=1":

drivers/scsi/gdth.c: In function ‘gdth_async_event’:
drivers/scsi/gdth.c:3010:9: warning: variable ‘cmd_index’ set but not
used [-Wunused-but-set-variable]
     int cmd_index;

Link: https://lore.kernel.org/r/20200909082627.101984-1-yebin10@huawei.comReported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/gdth.c

@@ -3007,7 +3007,6 @@ static char *async_cache_tab[] = {
 static int gdth_async_event(gdth_ha_str *ha)
 {
     gdth_cmd_str *cmdp;
-    int cmd_index;
 
     cmdp= ha->pccb;
     TRACE2(("gdth_async_event() ha %d serv %d\n",
@@ -3019,7 +3018,6 @@ static int gdth_async_event(gdth_ha_str *ha)
                 gdth_delay(0);
             cmdp->Service       = SCREENSERVICE;
             cmdp->RequestBuffer = SCREEN_CMND;
-            cmd_index = gdth_get_cmd_index(ha);
             gdth_set_sema0(ha);
             cmdp->OpCode        = GDT_READ;
             cmdp->BoardNode     = LOCALBOARD;