soc: qcom: Add a snapshot of QDSS bridge driver

This is the snapshot of the QDSS bridge driver as of msm-4.14 commit
4f22a43 (soc: qcom: qdss_bridge: Add spin_lock for accessing lists).
Use DEVICE_ATTR_RW for mode.

Change-Id: I5fcd2ea772ff47e5fc9e4c4b35a5f954e593e066
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>