msm: haptic: reduce haptic intensity except for calls and messages

Introduce a haptic duration threshold below which vibration intensity
is automatically reduced. The intensity of brief vibration is reduced
so that keyboard, touch, and fingerprint haptics are less audible. Add
sysfs nodes for accessing the threshold and the strong/light intensity
settings.

Bug: 31407746
Change-Id: Ib4704a38255f3171bb13fc2ecc0201940ffa8767