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/riscv/sbi.c

@@ -119,11 +119,8 @@ static int do_sbi(struct cmd_tbl *cmdtp, int flag, int argc,
 	return 0;
 }
 
-#ifdef CONFIG_SYS_LONGHELP
-static char sbi_help_text[] =
-	"- display SBI spec version, implementation, and available extensions";
-
-#endif
+U_BOOT_LONGHELP(sbi,
+	"- display SBI spec version, implementation, and available extensions");
 
 U_BOOT_CMD_COMPLETE(
 	sbi, 1, 0, do_sbi,