Documentation-getdelays: Apply a recommendation from "checkpatch.pl" in main()

The script "checkpatch.pl" pointed out that assignments should usually
not be performed within condition checks.
Thus move the assignment for the variable "nl_sd" to a separate statement.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>