kconfig: move CONFIG_OF_* to Kconfig

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 <[email protected]>
Acked-by: Simon Glass <[email protected]>
Cc: Stephen Warren <[email protected]>
Cc: Minkyu Kang <[email protected]>
Acked-by: Michal Simek <[email protected]>