net: qrtr: Ignore ENODEV failures in ns

Ignore the ENODEV failures returned by kernel_sendmsg(). These errors
mean either the local port has closed or the remote has gone down.
Neither of these scenarios are fatal and will eventually be handled
through packets that are later queued on the control port.

Also improve the logging messages to print the error code returned by
kernel_sendmsg().

Change-Id: Ibcebd1f44a3fbc87febaa84b11e05675663da5a0
Signed-off-by: Chris Lew <clew@codeaurora.org>