isdn: mISDN: correctly handle ph_info allocation failure in hfcsusb_ph_info

Modify return type of hfcusb_ph_info to int, so that we can pass error
value up the call stack when allocation of ph_info fails. Also change
three of four call sites to actually account for the memory failure.
The fourth, in ph_state_nt, is infeasible to change as it is in turn
called by ph_state which is used as a function pointer argument to
mISDN_initdchannel, which would necessitate changing its signature
and updating all the places where it is used (too many).

Fixes original flawed commit (38d22659) from the University of
Minnesota.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20210503115736.2104747-48-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>