power: qpnp-linear-charger: Add an led device controlled by LBC

Register an led device controlled by linear battery charger (LBC).
It can be used as a red indication led as well as a charging led.

Change-Id: I1ceb8af000ffdab0a2e1da3d3344487be5509678
Signed-off-by: Chunmei Cai <ccai@codeaurora.org>