arch/arm: add option to use *eabihf tuples

Toolchains that use the hard-float ABI now are to be denoted by a tuple
ending in *eabihf, while the prevbious *eabi is now an indication that
the toolchain uses the softfloat ABI.

This is purely a cosmetic thing, for distros to differentiate their
hardfloat-ABI ports from their softfloat-ABI ports.

(note: softfloat ABI does not mean that it is using softfloats; it can
be using hardfloat instructions, but using the softfloat ABI).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.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_SUPPORTS_WITH_ARCH

## select ARCH_SUPPORTS_WITH_TUNE

## select ARCH_SUPPORTS_WITH_FLOAT

##

## help The MIPS architecture, as defined by:

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