qcom: smb138x-charger: support two usb input properties

POWER_SUPPLY_PROP_INPUT_CURRENT_LIMITED - indicate if the switcher
	is acting in input limited state.
POWER_SUPPLY_PROP_CURRENT_MAX - set/get usb input current limit in
	parallel charger.

Change-Id: I3827735a3900680e3e79104e388c2712f12cbbfb
Signed-off-by: Harry Yang <harryy@codeaurora.org>