FreeBSD/src 0a0f40c (r354721)sys/riscv/include sbi.h md_var.h

Add missing files from r354720

MFC with:       r354720
Differential Revision:  https://reviews.freebsd.org/D22326
DeltaFile
+63-6sys/riscv/include/sbi.h
+3-0sys/riscv/include/md_var.h
+66-62 files

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