remote_bitbang: Change sleep commands to Zz to avoid conflict with SWD

remote_bitbang: Change sleep commands to Zz to avoid conflict with SWD

It was noticed that the remote_bitbang protocol has a design issue:
SWD and sleep commands cannot be implemented at the same time, because
they overlap:

 - SWD uses d,e,f,g for setting pin state
 - sleep uses d,D for microsecond and millisecond sleep, respectively

This has previously been reported by Marek Vrbka, but it wasn't fixed.

This commit does the following to resolve the issue:

 - Change the sleep commands to 'Z' for 1 ms, 'z' for 1 µs
 - Document 'D' and 'd' as deprecated aliases
 - Switch the remote_bitbang driver in OpenOCD to 'Z' and 'z'

Unfortunately that's a breaking change, because existing adapter-side
implementations of the protocol will have to implement the new commands
to keep working with future versions of OpenOCD. Fortunately, the
remote sleep commands haven't been part of an OpenOCD release yet,
which should limit the breakage somewhat.

Reported-by: Marek Vrbka <marek.vrbka@codasip.com>
Link: https://sourceforge.net/p/openocd/mailman/openocd-devel/thread/670d28d2-75a1-45ec-afe5-541415701d7a%40codasip.com/
Fixes: e8e09b1b5 ("remote_bitbang: add use_remote_sleep option to send delays to remote")
Change-Id: I04d2790a33bff9d47eb7f69b3275fd9a271625ae
Signed-off-by: J. Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.openocd.org/c/openocd/+/8191
Reviewed-by: David Ryskalczyk <david.rysk@gmail.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins
Reviewed-by: Jeremy Herbert <jeremy.006@gmail.com>