staging: r8723au: add & use local variable to simplify references

Add local variable scanned_queue to rtw_createbss_cmd23a_callback()
and use it (5x) to simplify references.

Addresses checkpatch.pl WARNING: line over 80 characters

Signed-off-by: Alison Schofield <amsfield22@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>