trace: make call depth limit customizable

Up to now we had hard coded values for the call depth up to which trace
records are created: 200 for early tracing, 15 thereafter. UEFI
applications reach a call depth of 80 or above.

Provide customizing settings for the call trace depth limit and the early
call trace depth limit. Use the old values as defaults.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>