dt-bindings: leds: Add Qualcomm Light Pulse Generator binding

[ Upstream commit a8e53db4 ]

This adds the binding document describing the three hardware blocks
related to the Light Pulse Generator found in a wide range of Qualcomm
PMICs.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Stable-dep-of: 609bc99a ("dt-bindings: leds: class-multicolor: Fix path to color definitions")
Signed-off-by: Sasha Levin <sashal@kernel.org>