LP1251424 - Fix for submit button when placing holds in staff client

I've moved the initializing of the cur_hold_barcode variable
to within the function rather than floating outside of it.
This seemed to fix an intermittent issue where the submit
button would not become activatable when first going to the
place hold screen via the staff client. To create the hold,
ths user had to cycle through the "Place hold by patron barcode"
option and then back to "Place hold for me" option.

It looked like behind the scenes for certain org units that
variable would not be set and the button will not open until
it at least has something. This causes it to be set on the initial
loading of the screen.

Signed-off-by: Steven Callender <stevecallender@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>