msm: msm_bus: Add bus clock aggregation

Bus clocks need to be aggregated at the entire topology level after
the aggregation at the node level during a transaction. This is because
bus driver has a single clock handle for each of its bus clocks and must
not assume any aggregation at the clock driver.

Change-Id: I2cc69ba71e611aee67e538db5e7134c52a439fa4
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>