criu --help: fix --external dev description

First, minor/major are separated by a slash, not a semicolon.

Second, use NAME not VAL.

travis-ci: success for Add/fix description of --external and --inherit-fd
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/crtools.c

@@ -820,12 +820,12 @@ usage:
 "                        Formats of RES on dump:\n"
 "                            tty[rdev:dev]\n"
 "                            file[mnt_id:inode]\n"
-"                            dev[maj:min]:VAL\n"
+"                            dev[major/minor]:NAME\n"
 "                            unix[ino]\n"
 "                            mnt[MOUNTPOINT]:COOKIE\n"
 "                            mnt[]{:AUTO_OPTIONS}\n"
 "                        Formats of RES on restore:\n"
-"                            dev[VAL]:DEVPATH\n"
+"                            dev[NAME]:DEVPATH\n"
 "                            veth[IFNAME]:OUTNAME{@BRIDGE}\n"
 "                            macvlan[IFNAME]:OUTNAME\n"
 "                            mnt[COOKIE]:ROOT\n"