This macro is slated for complete removal, as it's not possible
on arches with an MPU stack guard to know the true buffer bounds
without also knowing the runtime state of its associated thread.
As removing this completely would be invasive to where we are
in the 1.14 release, demote to a private kernel Z_ API instead.
The current way that the macro is being used internally will
not cause any undue harm, we just don't want any external code
depending on it.
The final work to remove this (and overhaul stack specification in
general) will take place in 1.15 in the context of #14269Fixes: #14766
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>