mtd: rename nand into rawnand in Kconfig prompt

Sync the Kconfig raw NAND entry title with the code architecture.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
index 1e4ea7b..008f7b4 100644
--- a/drivers/mtd/nand/raw/Kconfig
+++ b/drivers/mtd/nand/raw/Kconfig
@@ -1,6 +1,6 @@
 
 menuconfig NAND
-	bool "NAND Device Support"
+	bool "Raw NAND Device Support"
 if NAND
 
 config SYS_NAND_SELF_INIT