hal: Add open source HAL for Elliptic Ultrasound

Author: Balázs Triszka <balika011@gmail.com>
Date:   Mon Feb 26 22:11:10 2018 +0100

    msm8996: ultrasound: Initial open source hal for Elliptic Ultrasound

    * Needed for proximity sensor on Xiaomi Mi MIX

    Change-Id: Iaef2266bc1b853d7a9d1e2a906014c6c91019d5f
Signed-off-by: Balázs Triszka <balika011@gmail.com>

Author: Michael Bestas <mkbestas@lineageos.org>
Date:   Sat Feb 10 00:28:00 2018 +0200

    msm8996: ultrasound: Remove unused code

     * Params ultrasound_set_manual_calibration and ultrasound_set_sensitivity
       do not exist.

    Change-Id: I0004949db19b6ab7d49f20e422984e06a970cfe9

Author: Demon Singur <demonsingur@gmail.com>
Date:   Sat Apr 21 09:08:03 2018 +0000

    msm8996: hal: Update ultrasound route hacks

    Change-Id: If002503dfba0f005f73a4455d68bbcce9d2f617e

Change-Id: I798f5a8e4f25c4d192a95befd162b86495ccc178