interconnect: qcom: Use the standard aggregate function

Now we have a common function for standard aggregation, so let's use it,
instead of duplicating the code.

Reviewed-by: Brian Masney <masneyb@onstation.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>