tty: serial: 8250: serial_cs: Remove unused/unchecked variable 'err'

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

drivers/tty/serial/8250/serial_cs.c: In function ‘multi_config’:
drivers/tty/serial/8250/serial_cs.c:562:7: warning: variable ‘err’ set but not used [-Wunused-but-set-variable]

Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Jiri Slaby <[e-mail]>
Cc: Colin Ian King <[e-mail]>
Cc: "David A. Hinds" <[e-mail]>
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/8250/serial_cs.c

···
 	 */
 	if (info->manfid == MANFID_OXSEMI || (info->manfid == MANFID_POSSIO &&
 				info->prodid == PRODID_POSSIO_GCC)) {
-		int err;
-
 		if (link->config_index == 1 ||
 		    link->config_index == 3) {
-			err = setup_serial(link, info, base2,
-					link->irq);
+			setup_serial(link, info, base2, link->irq);
 			base2 = link->resource[0]->start;
 		} else {
-			err = setup_serial(link, info, link->resource[0]->start,
-					link->irq);
+			setup_serial(link, info, link->resource[0]->start,
+				     link->irq);
 		}
 		info->c950ctrl = base2;