imx6: aristainetos: fix NAND detection with latest mainline

commit 88718be30010 ("mtd: rename CONFIG_NAND -> CONFIG_MTD_RAW_NAND")
moved CONFIG_NAND -> CONFIG_MTD_RAW_NAND. Adapt board code to this
change, as last merge did not respect the above commit.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/board/aristainetos/aristainetos.c b/board/aristainetos/aristainetos.c
index c79ac1d..3541717 100644
--- a/board/aristainetos/aristainetos.c
+++ b/board/aristainetos/aristainetos.c
@@ -521,7 +521,7 @@
 };
 size_t display_count = ARRAY_SIZE(displays);
 
-#if defined(CONFIG_NAND)
+#if defined(CONFIG_MTD_RAW_NAND)
 iomux_v3_cfg_t nfc_pads[] = {
 	MX6_PAD_NANDF_CLE__NAND_CLE		| MUX_PAD_CTRL(NO_PAD_CTRL),
 	MX6_PAD_NANDF_ALE__NAND_ALE		| MUX_PAD_CTRL(NO_PAD_CTRL),