power: smb1355: enable device suspend

SMB1355 driver holds a wakeup source to avoid I2C transaction failure
during system suspend and thus causing high current consumption. Fix
I2C failures during suspend by reporting cached chip state during suspend
thus avoiding any I2C transaction during suspend.

Change-Id: I0ed214777a80b31ace944a79c5c473ec67dd89a7
Signed-off-by: Kavya Nunna <knunna@codeaurora.org>