tenderloin: Update CPU-specific optimizations

* Use new TARGET_CPU_VARIANT for Scorpion.
* Enable QCOM math optimizations.

Change-Id: I32fad7560e10fca871a9e12ede92c70932eb43c2
tenderloin: Set dynThreshold to 1.9 for hwcomposer

* Reduces jank during transitions

Change-Id: I1a44763ad091107ac4bb9132c37a7eaf34021539
tenderloin: enable Qualcomm AV enhancements

Change-Id: Ie7206779989b59b220f09170f671a9e361ab07c8
tenderloin: Set debug.mdpcomp.maxlayer=3

Change-Id: I0a612a9802e9bb042cc03d0c475ae4c41d655392
tenderloin: reboot fixups

* overlay: fw/b: don't show bootloader option in reboot menu
* init was trying to remove moboot.next after already remounting /boot readonly

Change-Id: I0aec07fbe265059447ee025010e5b10a3ac6a4c2