mtd: ensure MTD/the raw NAND core are compiled when there is a NAND flash

Both symbols must be enabled when there is a raw NAND driver
selected. Also enable them when CONFIG_CMD_NAND is selected to avoid
breaking things when we'll further rework the MTD dependency
description.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
[trini: Rebase and migrate a few more boards here]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/gardena-smart-gateway-at91sam_defconfig b/configs/gardena-smart-gateway-at91sam_defconfig
index 358098f..4173ff3 100644
--- a/configs/gardena-smart-gateway-at91sam_defconfig
+++ b/configs/gardena-smart-gateway-at91sam_defconfig
@@ -67,6 +67,7 @@
 CONFIG_LED=y
 CONFIG_LED_GPIO=y
 # CONFIG_MMC is not set
+CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y
 CONFIG_NAND_ATMEL=y
 CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER=y