soc: arm: mcimx6x_m4: Floating Point support required by default

The HAL/SDK code for imx6sx utilizes floating point support in
CCM_ANALOG_GetPllFreq function which is utilized by drivers to determine
clock information.  As such we should enable hardware FP support by
default so we don't get pure soft-float emulation and pull in a bunch of
extra code.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>