[media] cobalt: fix sparse warnings

[media] cobalt: fix sparse warnings

drivers/media/pci/cobalt/cobalt-irq.c:62:33: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:64:17: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:65:23: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:72:21: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:73:25: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:74:25: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:82:33: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:83:33: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:91:25: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:94:23: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:103:25: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:107:17: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:109:17: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:116:13: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:119:17: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:120:17: warning: dereference of noderef expression
drivers/media/pci/cobalt/cobalt-irq.c:122:17: warning: dereference of noderef expression

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>