Fix devpfs if starting telnetd

If we don't have devpts mounted, busybox telnetd will produce
"telnetd: can't find free pty" error.
Updated binaries:

u-boot: c14df54b2c4c6440bca577c4378501afcf86579e
kernel: d7baf3ddcc040497ca1e1e219ec8e79fcfd57482