msm: msm_bus: Program QoS registers only when needed

As part of the update bandwidth call, try to program the QoS registers
and enabling the QoS clocks only if the bus master is in limiter or
regulator mode. This will save on bus transaction times as enabling QoS
clocks can be an expensive operation if they're RPM controlled.

CRs-fixed: 720868
Change-Id: I76fe97792a944fb2e48729d9b00ca21d12d372e9
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>