ISDN: Add check for return value of pnp_activate_dev()

pnp_activate_dev() return value needs to be checked to make sure that
following calls calls to the PNP functions do work correctly.
Fix for report #44491 on bugzilla.kernel.org.
Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hisax/isurf.c

@@ -231,6 +231,11 @@ setup_isurf(struct IsdnCard *card)
 				}
 				pnp_disable_dev(pnp_d);
 				err = pnp_activate_dev(pnp_d);
+				if (err < 0) {
+					pr_warn("%s: pnp_activate_dev ret=%d\n",
+						__func__, err);
+					return 0;
+				}
 				cs->hw.isurf.reset = pnp_port_start(pnp_d, 0);
 				cs->hw.isurf.phymem = pnp_mem_start(pnp_d, 1);
 				cs->irq = pnp_irq(pnp_d, 0);