NFC: llcp: Add cleanup support for unreplied SNL requests

If the remote LLC doesn't reply in time to our SNL requests we remove
them from the list of pending requests. The timeout is fixed to an
arbitrary value of 3 times remote_lto.

When not replied, the local LLC broadcasts NFC_EVENT_LLC_SDRES nl events for
the concerned uris with sap values set to LLCP_SDP_UNBOUND (which is 65).

Signed-off-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>