qlcnic: fix a return in qlcnic_dcb_get_capability()

These functions are supposed to return one on failure and zero on
success.  Returning a zero here could cause uninitialized variable
bugs in several of the callers.  For example:

    drivers/scsi/cxgbi/cxgb4i/cxgb4i.c:1660 get_iscsi_dcb_priority()
    error: uninitialized symbol 'caps'.

Fixes: 48365e48 ("qlcnic: dcb: Add support for CEE Netlink interface.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>