ARM: renesas: Rename arch-/mach-rmobile to arch-/mach-renesas

Rename arch-rmobile to arch-renesas and mach-rmobile to mach-renesas
because all the chips are made by Renesas, while only a subset of
them is from the R-Mobile line.

Use the following command to perform the rename, with manual move of
the directories using git mv and manual fix up to arch/arm/Makefile:

"
$ git grep -l '\<\(arch\|mach\)-rmobile\>' | \
  xargs -I {} sed -i 's@\<\(arch\|mach\)-rmobile\>@\1-renesas@g' {}
$ sed -i 's@rmobile@renesas@' board/*/*/Kconfig
"

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>