power: smb-lib: use updated ICL override bit

Currently to override the ICL the self-clearing ICL override bit is
used. The problem with this bit is that it is self-clearing and a
separate register needs to be read to get the override status.
Furthermore, the hardware will automatically clear this bit on USB
removal.

A new ICL override bit was added in PMI hardware revision 2.0. This bit
is not self-clearing, and can be set prior to USB insertion. Use this
new bit.

Change-Id: I30a601b6aacba3c404ebdfb82e529504a694a048
Signed-off-by: Nicholas Troast <ntroast@codeaurora.org>