webadmin,userportal: Fix invalid CSS comment

CSS comments should follow /* Comment */ syntax.

Even though GWT compliation passes with HTML-like
comments in CSS, we should use proper comment syntax.

Change-Id: I6bba8093c8f924f4ad9a3b341bebc3ffcf94882c
Signed-off-by: Vojtech Szocs <vszocs@redhat.com>