gsmd: improve CFUN handling, and split 'init' state.

gsmd: improve CFUN handling, and split 'init' state.

Sometimes it can take a little while for CFUN to be effective.
So if it tells us the state is stil '0', we don't want to immediately
try the rest of the init process.

So split the init state into two - one which sets CFUN, and one
which is entered once CFUN says it is OK.

Also, if CFUN says it isn't OK in some way, trigger a reset, but
not too often.

Signed-off-by: NeilBrown <neilb@suse.de>