config: rename variables that are arrays

Make it explicit that a variable is an array bu the name of the variable.
It will be used later when .config gets munged to allow both multiple
arguments and arguments with spaces at the same time to be passed from the
configuration down to the build scripts.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# MIPS specific config options

## select ARCH_SUPPORTS_32

## select ARCH_SUPPORTS_64 if EXPERIMENTAL

## select ARCH_DEFAULT_32

## select ARCH_USE_MMU

## select ARCH_SUPPORTS_BOTH_ENDIAN

## select ARCH_DEFAULT_BE

## select ARCH_SUPPORT_ARCH

## select ARCH_SUPPORT_TUNE

##

## help The MIPS architecture, as defined by:

## help     http://www.mips.com/