arch/arm: ARM supports the softfp convention

ARM compilers can be built for soft float (software only, floats in
core registers), hard float (uses floating point instructions, floats
in FPU registers), or the half-way house softfp (uses floating point
instructions, floats in core registers).

Signed-off-by: Michael Hope <michael.hope@linaro.org>
[yann.morin.1998@anciens.enib.fr: split the original patch]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # x86 specific options

 ## select ARCH_SUPPORTS_32

 ## select ARCH_SUPPORTS_64

 ## select ARCH_DEFAULT_32

 ## select ARCH_USE_MMU

 ## select ARCH_SUPPORT_ARCH

 ## select ARCH_SUPPORT_CPU

 ## select ARCH_SUPPORT_TUNE

 ##

 ## help The x86 architecture, as defined by:

 ## help     32-bit (ia32) : http://www.intel.com/

 ## help     64-bit (amd64): http://www.amd.com/us-en/Processors/DevelopWithAMD/0,,30_2252_875_7044,00.html