updater: Add support for FKM OTA kernel updates

Link for users:
https://raw.githubusercontent.com/Zile995/android_kernel_xiaomi_msm8953/oreo-mr1/updater/update.json

Signed-off-by: Zile995 <stefan.zivkovic995@gmail.com>

Author: Zile995

updater/changelog

@@ -0,0 +1,9 @@
+Kernel: Underground Kernel
+Type: STABLE
+Device: Redmi Note 4(X) Snapdragon (mido)
+Compiler: AOSP Clang 10.0.1
+Branch: oreo-mr1
+
+- Latest Linux kernel updates from android-3.18 common tree (synced with sources up to January 13, 2020)
+- Anykernel3 updates
+- Added support for FKM OTA kernel updates

updater/update.json

@@ -0,0 +1,14 @@
+{
+  "kernel": {
+    "name": "Underground Kernel",
+    "version": "r42",
+    "link": "https://github.com/Zile995/android_kernel_xiaomi_msm8953/releases/download/r41/UndergroundKernel-mido-20200114.zip",
+    "changelog_url": "https://raw.githubusercontent.com/Zile995/android_kernel_xiaomi_msm8953/oreo-mr1/updater/changelog",
+    "date": "2020-01-14",
+    "sha1": "b39c46866c468d6bcf21bff28ecccedec5adb0b9"
+  },
+  "support": {
+    "link": "https://t.me/rn4official"
+  }
+}
+