Unlike the V3MSK and V3HSK boards, the various "ULCB" boards are really
the same boards, with different SiPs fitted, just like the Salvator-X(S)
boards.  Furthermore, the "H3", "M3", and "M3N" prefixes of the "ULCB"
parts in the DTS file names are redundant, as they are implied by the
SoC part numbers, which are also part of the file names.

Hence drop the redundant prefixes, to make the DTS file names consistent
with the file names for the various "Salvator-X(S)" boards.
Suggested-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20191217183841.432-3-geert+renesas@glider.be