rmmod: fix bad error message

    Before:

    ># busybox_old rmmod gtrhfhdfghdf
    rmmod: can't unload 'gtrhfhdfghdf': unknown symbol in module, or unknown parameter

    After:

    ># busybox rmmod gtrhfhdfghdf
    rmmod: can't unload module 'gtrhfhdfghdf': No such file or directory

function                                             old     new   delta
modprobe_main                                        726     721      -5
do_modprobe                                          599     590      -9
rmmod_main                                           187     169     -18
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-32)             Total: -32 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index 314a7a1..952ba03 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -461,9 +461,8 @@
 				rc = bb_delete_module(m2->modname, O_EXCL);
 				if (rc) {
 					if (first) {
-						bb_error_msg("can't unload module %s: %s",
-							humanly_readable_name(m2),
-							moderror(rc));
+						bb_perror_msg("can't unload module %s",
+							humanly_readable_name(m2));
 						break;
 					}
 				} else {
@@ -622,7 +621,7 @@
 			 * autoclean will be removed".
 			 */
 			if (bb_delete_module(NULL, O_NONBLOCK | O_EXCL) != 0)
-				bb_perror_msg_and_die("rmmod");
+				bb_perror_nomsg_and_die();
 		}
 		return EXIT_SUCCESS;
 	}