net: mctp: remove redundant RTN_UNICAST check

Current mctp_newroute() contains two exactly same check against
rtm->rtm_type

static int mctp_newroute(...)
{
...
    if (rtm->rtm_type != RTN_UNICAST) { // (1)
        NL_SET_ERR_MSG(extack, "rtm_type must be RTN_UNICAST");
        return -EINVAL;
    }
...
    if (rtm->rtm_type != RTN_UNICAST) // (2)
        return -EINVAL;
...
}

This commits removes the (2) check as it is redundant.

Signed-off-by: Lin Ma <linma@zju.edu.cn>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20230615152240.1749428-1-linma@zju.edu.cn


Signed-off-by: Jakub Kicinski <kuba@kernel.org>