Adding a dependency on ourselves in this function doesn't make sense, the hash
may change after hash equivalence is applied. Other code using BB_TASKDEPDATA does
handle the self reference correctly (which is there for a reason), update this
code to do likewise.
(From OE-Core rev: d98b06c9c6f480de1e5167bfe8392e39300fc02c)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>