mtd: move NAND files into a raw/ subdirectory

NAND flavors, like serial and parallel, have a lot in common and would
benefit to share code. Let's move raw (parallel) NAND specific code in a
raw/ subdirectory, to ease the addition of a core file in nand/ and the
introduction of a spi/ subdirectory specific to SPI NANDs.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
diff --git a/drivers/Makefile b/drivers/Makefile
index 23ea609..fe8d40d 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -6,7 +6,7 @@
 obj-$(CONFIG_$(SPL_TPL_)I2C_SUPPORT) += i2c/
 obj-$(CONFIG_$(SPL_TPL_)LED) += led/
 obj-$(CONFIG_$(SPL_TPL_)MMC_SUPPORT) += mmc/
-obj-$(CONFIG_$(SPL_TPL_)NAND_SUPPORT) += mtd/nand/
+obj-$(CONFIG_$(SPL_TPL_)NAND_SUPPORT) += mtd/nand/raw/
 obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
 obj-$(CONFIG_$(SPL_TPL_)PINCTRL) += pinctrl/
 obj-$(CONFIG_$(SPL_TPL_)RAM) += ram/