cmd: mtd: expand <name> argument definition in command help

The <name> argument can now also be MTD's DM device name or OF path.
Mention this is command help.

Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Cc: Priyanka Jain <priyanka.jain@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Heiko Schocher <hs@denx.de>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/cmd/mtd.c b/cmd/mtd.c
index 2aabfd4..c22478c 100644
--- a/cmd/mtd.c
+++ b/cmd/mtd.c
@@ -542,7 +542,7 @@
 	"mtd bad                               <name>\n"
 	"\n"
 	"With:\n"
-	"\t<name>: NAND partition/chip name\n"
+	"\t<name>: NAND partition/chip name (or corresponding DM device name or OF path)\n"
 	"\t<addr>: user address from/to which data will be retrieved/stored\n"
 	"\t<off>: offset in <name> in bytes (default: start of the part)\n"
 	"\t\t* must be block-aligned for erase\n"