UBUNTU: SAUCE: (snapdragon) DT: leds: Add Qualcomm Light Pulse Generator binding

UBUNTU: SAUCE: (snapdragon) DT: leds: Add Qualcomm Light Pulse Generator binding

BugLink: http://bugs.launchpad.net/bugs/1763040
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>
Signed-off-by: Ramon Fried <rfried@codeaurora.org>
(cherry picked from commit 780bb8370eb249be9a66084ea58482254e6a4c23
http://git.linaro.org/landing-teams/working/qualcomm/kernel.git release/qcomlt-4.14)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>