imx6: enable FPU for hard float

imx6: enable FPU for hard float

The OpenWrt build system uses MACHINE_FEATURES of fpu to set the HAS_FPU which
in turn sets the default of CONFIG_SOFT_FLOAT as well as uClibc configuration.
As the IMX6 SoC has both vfpv3 and NEON hardware support we want to add fpu
to the feature list.  This will default the IMX6 target to use -mfloat-abi=hard
which will the be most efficient use of floating point.

When switching to hard float, we also need to enable VFP support in the kernel.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39759 3c298f89-4303-0410-b956-a3cf2f4a3e73