NFC: st21nfcb: Configure CLF with NCI proprietary command

In order to prevent any NFC feature when NFC is disable and
to save power, (down to 4uA) put the CLF in hibernate mode
with RF deactivated.
Add the equivalent to enable the NFC feature when initiating
the st21nfcb driver.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>