Make internal clock sourcing work right by tying the NCO to the

Make internal clock sourcing work right by tying the NCO to the
Xtal reference instead of the CLADI input.

In unframed E1 mode, tie SIGFRZ low so that the mysycc doesn't
get confused.

Don't mask errors with OOF.  Don't ignore OOF errors.

Stop the channel before freeing mbufs in disconnect.

I still have no T1 devices to test with, so the T1 code is non-existent.