msm: camera: common: Add sysfs support for bw override

To simulate bus overflow recovery in camera, cpas needs sysfs
to take input from shell and vote the final value as given,
instead of consolidated values from cpas clients. Add initial
support for sysfs to add nodes for all drivers. Add sysfs
based debug node to maintain and update all settings. Add cpas
settings to override final bw voted to camnoc and mnoc ports.

Usage:
adb shell "echo <driver_name>#<setting_name>=<value>
> /sys/devices/platform/soc/soc:qcom,cam-req-mgr/debug_node"

Example:i
adb shell "echo cpas#camnoc_bw=100
> /sys/devices/platform/soc/soc:qcom,cam-req-mgr/debug_node"

Input format for updating settings is strict.

CRs-Fixed: 2646825
Change-Id: I8d6063240f9685474bf4b2899e8dfb3f74cbdb75
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>