This function starts up a PPP connection. The
devnam argument is the name of the device to be
used for the connection, typically "/dev/ser0" or
argument should point to an initialized
The return value will either be zero, indicating a failure, or a cyg_ppp_handle_t object that may be used as an argument to other PPP functions.
Note: Although the PPP API is designed to permit several simultaneous connections to co-exist, at present only one PPP connection is actually implemented. Any attempt to create a second connection while there is already one open will fail.