qcom-charger: smb2: configure input from wipower

Wipower feeds to the DCIN input of the smb2 charger and relies on
input current configurations on six different voltage ranges for
optimal power draw.

Provide means to configure the current limits in them via a device
tree setting.

Change-Id: I81d1dc3ed1d588d67525b15120e7d8b947536099
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>