cmd/rng: fix long help text

The number of bytes may only be specified if a device number id provided.

Correct the formatting.

Acked-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
(cherry picked from commit 528b6b817e)

cmd/rng.c

@@ -75,6 +75,6 @@ static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 U_BOOT_CMD(
 	rng, 3, 0, do_rng,
 	"print bytes from the hardware random number generator",
-	"list         - list all the probed rng devices\n"
-	"rng [dev] [n]    - print n random bytes(max 64) read from dev\n"
+	"list          - list all probed rng devices\n"
+	"rng [dev [n]] - print n random bytes (max 64) read from dev\n"
 );

doc/usage/cmd/rng.rst

@@ -12,14 +12,14 @@ Synopsis
 ::
 
     rng list
-    rng [dev] [n]
+    rng [dev [n]]
 
 rng list
 --------
 
 List all the probed rng devices.
 
-rng [dev] [n]
+rng [dev [n]]
 -------------
 
 The *rng* command reads the random number generator(RNG) device and