power: smb1360: Add an optional property to set OTG current threshold

Add an optional property to set the current draw from battery when
device working at OTG mode.

CRs-Fixed: 695044
Change-Id: I2167c7e58bfb6cb81741e3ea000197a9e1751fcf
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>