ARM: dts: msm: Add slimbus slave device for wcn3990 on sdm670

Slimbus is used as audio transport for Bluetooth & FM between sdm670 &
wcn3990. Add device tree entry for wcn3990 slimbus slave device in sdm670.

Change-Id: I6a5f2d45a2f8ae7b8c53db6814d81e10b858d19c
Signed-off-by: Rupesh Tatiya <rtatiya@codeaurora.org>