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

Configure temperature buffer output of slave CP to high impedance
since in H/W 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>