"Pad size" just doesn't make much sense. Let's go with "Buffer size"
instead, since the control for it is labeled "Buffer".
(Another possibility is "Pad buffer size", but I'm against that,
because we've stopped referring to controllers as "pads" in almost
all GUI strings.)
Settings that come from the SYSCONF are now included in Dolphin's
config system as part of the base layer. They are handled in a
special way compared to other settings to make sure they are only
loaded from and saved to the SYSCONF (to avoid different, possibly
contradicting sources of truth).
