ARM: dts: msm: Enable gsi device on sdm670

Add gsi device node on SDM670 which
is needed for IPA HW to be functional.

Change-Id: I3ec9383fc65d5ec6c30a788bddf641f9cd3ef0bc
Acked-by: Ashok Vuyyuru <avuyyuru@qti.qualcomm.com>
Signed-off-by: Mohammed Javid <mjavid@codeaurora.org>