Fix warnings about implicit declarations

Two functions were used without including header file
and generating following warnings:

implicit declaration of function 'bta_sys_add_uuid'
implicit declaration of function 'bta_sys_remove_uuid'

Change-Id: I1c36fda7af9e838259b93bd2a29e3547d9df0eb5
Signed-off-by: Mike J. Chen <mjchen@google.com>