of: flip CONFIG_SPL_DISABLE_OF_CONTROL into CONFIG_SPL_OF_CONTROL

As we discussed a couple of times, negative CONFIG options make our
life difficult; CONFIG_SYS_NO_FLASH, CONFIG_SYS_DCACHE_OFF, ...
and here is another one.

Now, there are three boards enabling OF_CONTROL on SPL:
 - socfpga_arria5_defconfig
 - socfpga_cyclone5_defconfig
 - socfpga_socrates_defconfig

This commit adds CONFIG_SPL_OF_CONTROL for them and deletes
CONFIG_SPL_DISABLE_OF_CONTROL from the other boards to invert
the logic.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/socfpga_arria5_defconfig b/configs/socfpga_arria5_defconfig
index 4d1cd21..f406db7 100644
--- a/configs/socfpga_arria5_defconfig
+++ b/configs/socfpga_arria5_defconfig
@@ -6,6 +6,7 @@
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_FLASH is not set
 CONFIG_OF_CONTROL=y
+CONFIG_SPL_OF_CONTROL=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPL_DM=y
 CONFIG_SPL_MMC_SUPPORT=y