dyndbg: refactor parse_linerange out of ddebug_parse_query

Make the code-block reusable to later handle "file foo.c:101-200" etc.
This is a 99% code move, with reindent, function wrap&call, +pr_debug.

no functional changes.

Acked-by:  <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-13-jim.cromie@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>