update the 4.14 and 4.19 prebuilt kernels am: 7f0d0dcd40 am: 8b8fccd142

Original change: https://android-review.googlesource.com/c/device/ti/beagle-x15-kernel/+/1892515

Change-Id: Ibe45a08168936fdc4a199c0eb6f256bc2f90da5a