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/doc/README.arm-relocation b/doc/README.arm-relocation
index 645b374..d2a7e81 100644
--- a/doc/README.arm-relocation
+++ b/doc/README.arm-relocation
@@ -84,7 +84,7 @@
 - cpu copies the first page from NAND to 0xbb000000 (IMX_NFC_BASE)
   and start with code execution on this address.
 
-- The First page contains u-boot code from drivers/mtd/nand/mxc_nand_spl.c
+- The First page contains u-boot code from drivers/mtd/nand/raw/mxc_nand_spl.c
   which inits the dram, cpu registers, reloacte itself to CONFIG_SPL_TEXT_BASE	and loads
   the "real" u-boot to CONFIG_SYS_NAND_U_BOOT_DST and starts execution
   @CONFIG_SYS_NAND_U_BOOT_START