Clarify context source

[bcstrongx]

The description for the trTeContext bit says:

Enable sending trace messages/fields with scontext/mcontext values and/or privilege levels.

This should be modified to allow the hart to deliver other context identifiers, like VMID+ASID, as the Debug and E-trace specs allow. I would recommend replacing "scontext/mcontext" with "context", then adding a non-normative passage referring to options for sending scontext/mcontext or VMID/ASID.

[mipsrobert]

Thanks @bcstrongx - I somehow missed it. I will not edit the spec - I want to do it with some other small changes. I keep these issues open.

[bcstrongx]

I noticed that the Trace Control Interface spec also needs a similar update.