dts: arm: Kinetis: Add FRDM_K64F support

This patch adds DTS support for the FRDM_K64F board.  The defconfig
enables the DTS usage and the FRDM K64F specific DTS file provides the
differences from the base Kinetis DTS definitions.

A fixup file is provided to map the generated configuration information
to the driver consumers.  The fixup file will be removed once the
drivers are modified to handle the newly generated information.

Change-Id: Ib0ada28faff6a30e8b40eba5c5853e9018ae5fcb
Signed-off-by: Andy Gross <andy.gross@linaro.org>