power: smb1360: Add a dummy read to probe SMB1360

There is a possibility that the SMB1360 may not be
physically present on the board. Add a dummy read
to check if the device probes and bail out if it
fails.

Change-Id: Id098e47f4064f2e359c3d1978f2f3846dd841d41
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>