dyndbg: fix pr_err with empty string

this pr_err attempts to print the string after the OP, but the string
has been parsed and chopped up, so looks empty.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-9-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

lib/dynamic_debug.c

@@ -420,7 +420,7 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 			}
 		}
 		if (i < 0) {
-			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
+			pr_err("unknown flag '%c'\n", *str);
 			return -EINVAL;
 		}
 	}