cmd: clk: fix long help message

Fix the long help message for "clk setfreq" command

Fixes: 7ab418fb ("clk: add support for setting clk rate from cmdline")
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
Link: https://lore.kernel.org/r/20220131172131.4.Ic863c28ffdcc15b3f4616434c2efd88b4e45495c@changeid

cmd/clk.c

@@ -160,7 +160,7 @@ static int do_clk(struct cmd_tbl *cmdtp, int flag, int argc,
 #ifdef CONFIG_SYS_LONGHELP
 static char clk_help_text[] =
 	"dump - Print clock frequencies\n"
-	"setfreq [clk] [freq] - Set clock frequency";
+	"clk setfreq [clk] [freq] - Set clock frequency";
 #endif
 
 U_BOOT_CMD(clk, 4, 1, do_clk, "CLK sub-system", clk_help_text);