zephyr: frdm_k64f: Remove partition defines
zephyr: frdm_k64f: Remove partition defines

Now that the partition table has been added to the device tree for the
frdm_k64f in upstream Zephyr, these symbols become redundant defines.
Remove them to fully use the partitions defined in Zephyr.

Signed-off-by: David Brown <0af22db655f3ade5845314d695c1f4910314b0cb@linaro.org>

utzig/mcuboot,tamban01/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,utzig/mcuboot,ATmobica/mcuboot,tamban01/mcuboot,tamban01/mcuboot,runtimeco/mcuboot,utzig/mcuboot,tamban01/mcuboot,runtimeco/mcuboot,utzig/mcuboot,tamban01/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,utzig/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot