wcnss: configure iris into cxo mode

configure iris into cxo mode when iris card not present
to avoid crash at boot time.

Change-Id: I5efd0fb704e2e534a3b608bc1e80f5d6a53a02aa
CRs-fixed: 691946
Signed-off-by: Hardik Kantilal Patel <hkpatel@codeaurora.org>