ipa: Partially revert the e1inp_ipa_bts_rsl_connect_n commit

The check was always hit by osmo-bts master leading to the RSL
connection never being made. This is because the type of the line
will be set _after_ the RSL connection has been made. E.g. inside
osmo-bts/src/common/abis.c:

static struct e1inp_sign_link *sign_link_up(void *unit, struct e1inp_line *line,
                                            enum e1inp_sign_type type)
{
        struct e1inp_sign_link *sign_link = NULL;

        switch (type) {
	...
        case E1INP_SIGN_RSL:
                LOGP(DABIS, LOGL_INFO, "RSL Signalling link up\n");
                e1inp_ts_config_sign(&line->ts[E1INP_SIGN_RSL-1], line);
	...

Only the call to e1inp_ts_config_sign will set the type to be
E1INP_TS_TYPE_SIGN. Before the call the type is still _NONE and
the connect was rejected.