arch: riscv: add support for building DTB files from DT source data
Similar to ARM64, add support for building DTB files from DT source
data for RISC-V boards.
This patch starts with the infrastructure needed for SiFive boards.
Boards from other vendors would add support here in a similar form.
Signed-off-by: Paul Walmsley <paul.walmsley at sifive.com>
Signed-off-by: Paul Walmsley <paul at pwsan.com>
Tested-by: Loys Ollivier <lollivier at baylibre.com>
Tested-by: Kevin Hilman <khilman at baylibre.com>
Cc: Palmer Dabbelt <palmer at sifive.com>
Cc: Albert Ou <aou at eecs.berkeley.edu>
UnifiedSplitRaw
