power: smb1390-psy: Configure temperature output buffer to High-Z state

Configure temperature buffer output of slave CP to high impedance
since in HW we are only reading temperature for Master CP and
temperature of slave CP is assumed same as that of Master due to
physical proximity between them.

Change-Id: I4f9b8bf0baaf7435c3770bb573bb1a27dd5062b6
Signed-off-by: Sahil Chandna <chandna@codeaurora.org>