tspp: Protect against buffer overflow

Change filter->priority to unsigned int. Since it was defined as integer,
it may have had negative value and cause accessing an array outside
of its region

CRs-Fixed: 561802, 561825
Change-Id: Ie72aa09b07e79b0b67081b74e3b2057de30f03d0
Signed-off-by: Oded Bar <obar@codeaurora.org>