NFC: nci: Add NFCEE enabling and disabling support

NFCEEs can be enabled or disabled by sending the
NCI_OP_NFCEE_MODE_SET_CMD command to the NFCC. This patch
provides an API for drivers to enable and disable e.g. their
NCI discoveredd secure elements.

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