ARM: uniphier: move CONFIG_NAND to defconfig

This imply was added when the option was moved by the moveconfig tool,
but the intention is not clear.  Move it to defconfig.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/configs/uniphier_pxs2_ld6b_defconfig b/configs/uniphier_pxs2_ld6b_defconfig
index a7b517e..4ab56d8 100644
--- a/configs/uniphier_pxs2_ld6b_defconfig
+++ b/configs/uniphier_pxs2_ld6b_defconfig
@@ -36,6 +36,7 @@
 CONFIG_MISC=y
 CONFIG_I2C_EEPROM=y
 CONFIG_MMC_UNIPHIER=y
+CONFIG_NAND=y
 CONFIG_NAND_DENALI=y
 CONFIG_NAND_DENALI_DT=y
 CONFIG_SYS_NAND_DENALI_64BIT=y