Pixel Experience Plus - RMX1851

* September Security patch

* Proper model detection (supported models: RMX1851, RMX1853, RMX1855)

* Realme settings improvements

* Performance mode just like RUI High performance mode, works along game mode option inside Realme settings. (Disable it after gaming so that it will switch to balanced profile)

* Game mode DND improvements

* Added F2fs mount point

* Added support for realme X Lite (audio should work now)

* Enabled zygote preforking (Faster app launch)

Changelog for 12/10/2020

* Added App Lock

* October Security Patch

* Updated vendor security patch

* Updated build fingerprint and description

* Updated Camera blobs

* Switched to QTI Bluetooth Stack

* SE Linux improvements

* game mode tunings

* Kernel upstream