sys: Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

dtb: freescale: Add fsl-ls1028a-rdb to the build

With the recent inclusion of ENETC networking driver we now support this
board.

Obtained from: Semihalf
Sponsored by: Alstom Group

Connect DTB files based on LX2160A SoC to build.
Mainly LX2K Honeycomb and ClearFog-CX boards.