Bug 29895: Fix 'add multiple items' button on neworderempty

Bug 29895: Fix 'add multiple items' button on neworderempty

Button [Add multiple items] stops responding when it's pressed and some multiple items added to basket

It has a "visibility: hidden" we are trying to remove setting "display:
inline"

This is pretty ugly and certainly does not clean the code, but it's too
messy and this patch fixes the problem easily.

Test plan:
Add a new order
Click "Add multiple items", enter "2", click "Add".
Confirm that you can use the "Add multiple items" again.

Signed-off-by: Samu Heiskanen <samu.heiskanen@hypernova.fi>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>