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>

# Bare metal config options

## select BARE_METAL

##

## help 'Bare metal' refers to those programs that run without any kernel.

## help

## help You probably want to say 'y' here if you plan to use your compiler

## help to build bootloaders. It is not yet suitable to build Linux kernels,

## help though, because the APCI stuff relies on the target C library headers

## help being available?!?!...