msm: camera: cci: Add serialization of requests from diff i2c freq modes

Subdevs might request CCI master to run at different i2c frequency modes.
If a different frequency is requested for a master, requests with previous
frequency are completed before it can be set to the new frequency.

Change-Id: I90714e07c7f8ca50dfd3a5d6ef94cbc85c03ef3c
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>