cmd: Convert existing long help messages to the new macro

- Generally we just drop the #ifdef CONFIG_SYS_LONGHELP and endif lines
  and use U_BOOT_LONGHELP to declare the same variable name as before
- In a few places, either rename the variable to follow convention or
  introduce the variable as it was being done inline before.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

cmd/clk.c

@@ -152,10 +152,8 @@ static int do_clk(struct cmd_tbl *cmdtp, int flag, int argc,
 		return CMD_RET_USAGE;
 }
 
-#ifdef CONFIG_SYS_LONGHELP
-static char clk_help_text[] =
+U_BOOT_LONGHELP(clk,
 	"dump - Print clock frequencies\n"
-	"clk setfreq [clk] [freq] - Set clock frequency";
-#endif
+	"clk setfreq [clk] [freq] - Set clock frequency");
 
 U_BOOT_CMD(clk, 4, 1, do_clk, "CLK sub-system", clk_help_text);