msm: camera: Enhancements to soc layer

Define camera bus clients to identify the multiple camera clients.
Add API to support devices consisting of multiple clock rates
in the device tree node and register threaded irq.

Change-Id: Icdaae68b82c441baf988e90fb6d5cc83c2402a93
Signed-off-by: Lakshmi Narayana Kalavala <lkalaval@codeaurora.org>