dt-bindings: qcom: smb1390: Add snapshot

Add snapshot of the dt-bindings of the SMB1390 driver as of msm-4.14
'commit 2af01acb8e045 ("clk: qcom: gdsc: Remove global mutex lock in
enable/disable callbacks")'.

Change-Id: If229a89ebefb62c5a635f2a50a6cdddece8ae8a2
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>