power: smb-lib: Improve the OTG enable workaround for PM660

There are scenarios where inductive load with higher inrush
current may fail to turn on the OTG. Improve the OTG turn-on
sequence by gradually increasing the current-limit if it
fails to turn-on with a lower current.

Change-Id: I41c1e25257a4ee87f00287e07773331b1445b5f2
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>