kconfig: move CONFIG_OF_* to Kconfig

This commit moves:
  CONFIG_OF_CONTROL
  CONFIG_OF_SEPARATE
  CONFIG_OF_EMBED
  CONFIG_OF_HOSTFILE

Because these options are currently not supported for SPL,
the "Device Tree Control" menu does not appear in the SPL
configuration.

Note:
zynq-common.h should be adjusted so as not to change the
default value of CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>