This makes the open symmetrical with the close. It is also considered good
practice to not call through callbacks with spinlocks held.
I modified all the drivers where I could not tell whether it was necessary to
hold the chan->lock with interrupts disabled to simply take the lock inside the
callback.
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>
b3a6b91858