power: smb1360: Use the previous property value when suspended

i2c calls fail after the device is suspended. To avoid
returning error values, return the previous value of
of a power-supply property if requested after suspend.

CRs-Fixed: 819982
Change-Id: Ibad6872e8e5e576aaad0e7c4dab6b4d7375fa107
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>