msm: tspp2: Support working without bus scaling

The TSPP2 driver uses the bus scaling API to request bus bandwidth.
However, bus scaling can be completely disabled.
Add support to allow the TSPP2 driver to work even when bus scaling
is disabled.

Change-Id: I0a4cbd8f705aa6fb673b1a4d1ffe13c057e1d450
Signed-off-by: Liron Kuch <lkuch@codeaurora.org>