Revert "platform/chrome: Don't make CHROME_PLATFORMS depends on X86 || ARM"

This reverts commit d12bbcd3 ("platform/chrome: Don't make
CHROME_PLATFORMS depends on X86 || ARM") since it was found to
not be the correct fix for the MFD_CROS_EC config unmet direct
dependencies warning.

The correct solution was to add the needed dependencies to the
MFD_CROS_EC symbol. Besides the revert, this patch extends the
CHROME_PLATFORMS symbol dependencies and adds || COMPILE_TEST
to allow drivers to have build coverage on other architectures.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Olof Johansson <olof@lixom.net>