Make hard-float the default on Cortex-A8 and Cortex-A9

Cortex-A8 and Cortex-A9 ARM cores are guaranteed to provide a hardware
floating point unit, so there's no reason to default to software
floating point for them.

More importantly, the newest Linaro toolchains are hard float
toolchains, so basically an user choosing those toolchains and leaving
the default option of software float would run in compilation issues.

So let's make hard float the default for Cortex-A8 and Cortex-A9.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>