The modem sockets poll implementation does not allow
a combination of poll on modem sockets and on other sockets
like eventfd. This blocks trivial application signalling. Current
users are using a poll timeout, which needs to check if other
work needs to be done in the thread (eg: lwm2m engine).
To allow proper signalling with eventfd, the non offload poll
methods needs to work for the modem sockets.
This commit is implementing this for POLLIN.
Signed-off-by: Wouter Cappelle <wouter.cappelle@crodeon.com>