release_irq label is only used when ALLOW_DMA is defined.

drivers/net/cs89x0.c: In function 'net_open':
drivers/net/cs89x0.c:1401: warning: label 'release_irq' defined but not used
Signed-off-by: NYoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>