mgcp: Remove the endp_offset that was introduced due coding stupidity

The endpoint offset is needed for two reasons, first the API is 0
based here while we are normally 1 based, second because of the trunks
the first usable endpoint would be '2' (0 is CRC, 1 is signalling), but
this endpoint offset falls apart when we would block timeslots inside
this range.

Remove the endpoint offset, in each endpoint we will store the HW DSP
Port (1 based API) and then subtract one to get to the 0 based API for
the Simple API. Print a warning when someone is using the endpoint offset.
5 files changed