libc: make ttyname(3) use devname(3)
libc: make ttyname(3) use devname(3)

There was an off-by-one in the old MINIX-specific implementation,
which caused ttyname(3) to fail at random. Since we now have a working
devname(3), there is no need for MINIX-specific code anymore here.

Change-Id: I27d8b6c4f66c84f383156ed494b740d071af02a7

veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi