msm: msm_bus: Add snapshot of msm_bus driver

Initial port of msm bus codebase into new kernel version from msm-4.4,
commit f600d8b9ec91f ("msm-core: Move get_user out side critical section")

Change-Id: I596f206fc841f46ac08b963093680df26255917c
Signed-off-by: David Dai <daidavid1@codeaurora.org>
diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 519eea9..acc6e1f 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -184,3 +184,11 @@
 	  subsystems to register respective dump regions. At the time
 	  of deadlocks or cpu hangs these dump regions are captured to
 	  give a snapshot of the system at the time of the crash.
+
+config QCOM_BUS_SCALING
+	bool "Bus scaling driver"
+	help
+	This option enables bus scaling on MSM devices.  Bus scaling
+	allows devices to request the clocks be set to rates sufficient
+	for the active devices needs without keeping the clocks at max
+	frequency when a slower speed is sufficient.