NFC: NCI: export nci_send_frame and nci_send_cmd function

Export nci_send_frame and nci_send_cmd symbols to allow drivers
to use it. This is needed for example if NCI is used during
firmware download phase.

Signed-off-by: Vincent Cuissard <cuissard@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>