aaa: Suppress compiler warnings for unchecked cast

Suppress two compiler warnings for unchecked casts
There is no more targeted approach for suppressing it properly in
NegotiationFilter, hence the "unchecked" warnings are suppressed
for the complete doFilter method.

Topic: AAA
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1120720
Change-Id: I730d91cdb7392f91e475642230a5c499f235f73c
Signed-off-by: Tim Speetjens <tim.speetjens@redhat.com>