Improve including of architecture dependent Kconfig files.

- Always include the architecture dependent Kconfig files.
- Wrap architecture dependent Kconfig files inside an appropriate
  "if ETRAX_ARCH_Vxx" block.

This makes it possible to run the configuration even without the arch links,
which are created later in the build process.
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>