slim_msm: Move out common functionality from MSM controller driver

Starting with new platforms, MSM slimbus controller can operate in
master mode or satellite mode. (Not in both modes for the same build)
Move out common functional code from the controller driver that can
be reused by satellite mode and master mode.

Change-Id: Idbc3fa93067f67f645981071ff6ad457c284576f
Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>