configs: ks2: move CMD_NAND to defconfigs

NAND is not yet enabled on all Keystone2 platforms. So enabled
CMD_NAND in the respective defconfigs only if available.

Reported-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/k2e_evm_defconfig b/configs/k2e_evm_defconfig
index f45bce0..c843508 100644
--- a/configs/k2e_evm_defconfig
+++ b/configs/k2e_evm_defconfig
@@ -16,3 +16,4 @@
 CONFIG_DM_ETH=y
 CONFIG_SYS_NS16550=y
 CONFIG_TI_AEMIF=y
+CONFIG_CMD_NAND=y
diff --git a/configs/k2hk_evm_defconfig b/configs/k2hk_evm_defconfig
index 56b3fe4..1627065 100644
--- a/configs/k2hk_evm_defconfig
+++ b/configs/k2hk_evm_defconfig
@@ -16,3 +16,4 @@
 CONFIG_DM_ETH=y
 CONFIG_SYS_NS16550=y
 CONFIG_TI_AEMIF=y
+CONFIG_CMD_NAND=y
diff --git a/configs/k2l_evm_defconfig b/configs/k2l_evm_defconfig
index 3863c56..255f6d1 100644
--- a/configs/k2l_evm_defconfig
+++ b/configs/k2l_evm_defconfig
@@ -16,3 +16,4 @@
 CONFIG_DM_ETH=y
 CONFIG_SYS_NS16550=y
 CONFIG_TI_AEMIF=y
+CONFIG_CMD_NAND=y
diff --git a/include/configs/ti_armv7_keystone2.h b/include/configs/ti_armv7_keystone2.h
index 61c7174..be3c299 100644
--- a/include/configs/ti_armv7_keystone2.h
+++ b/include/configs/ti_armv7_keystone2.h
@@ -208,7 +208,6 @@
 #define CONFIG_CMD_DHCP
 #define CONFIG_CMD_PING
 #define CONFIG_CMD_SAVES
-#define CONFIG_CMD_NAND
 #define CONFIG_CMD_UBI
 #define CONFIG_CMD_UBIFS
 #define CONFIG_CMD_SF