b658113064
FDT_DTS_FILE was built separately with a rule in sys/conf/files and recreated the rules we used in dtb.mk. Now that we have other infrastructure to build a DTB along with the kernel, fold FDT_DTS_FILE into that since it doesn't have any special requirements. fdt(4) never got revised to mention the DTS/DTSO make options, so do that now. Reviewed by: imp MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D19736