presets: remove moldering iPod presets

* Some users are trying to use them for non-ancient iDevices when
  baseline profile and level 1.3/3.0 would not be required.

* "640" and "320" no longer make sense.

* Some recommended options can be viewed at:
  <https://trac.ffmpeg.org/wiki/Encode/H.264#iOS>
Signed-off-by: Lou Logan <lou@lrcd.com>
Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

presets/libx264-ipod320.ffpreset

-vcodec=libx264
-
-vprofile=baseline
-level=13
-maxrate=768000
-bufsize=3000000

presets/libx264-ipod640.ffpreset

-vcodec=libx264
-
-vprofile=baseline
-level=30
-maxrate=10000000
-bufsize=10000000