power: smb1360: Add a DT property to configure minimum ICL

On removal of USB charger the input current limit (ICL)
needs to be configured to a minimum value. Add a DT
property to allow this value to be configured to USB100
or USB500.

Configuring this value to USB500 does not adhere to the
USB charging spec. but guarantees that the minimum
charging current in all scenarios is 500mA. Setting
this value to USB100 follows the USB spec but can
drastically increase the charging time during pre-charge.

Use a default value of USB500.

CRs-Fixed: 713576
Change-Id: I094ac520437b24ecb4f5fc81c8b8898bb7ed9a65
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>