Revert "ldlinux: Allow a held shift key to override UI as well as DEFAULT"

Revert "ldlinux: Allow a held shift key to override UI as well as DEFAULT"

This reverts commit 7e7139788c8ac6ffbf474976ad4d1727e0677b9f.

Requested by Ady <ady-sf@hotmail.com> who also requested the original
patch:

After some tests with MENU SHIFTKEY with different versions of
Syslinux, I came to the conclusion that, at least for now, it would
be better to undo commit 7e7139788c8ac6ffbf474976ad4d1727e0677b9f:

 "ldlinux: Allow a held shift key to override UI as well as DEFAULT"
committed on Thu, 22 May 2014.

Although the aforementioned commit makes the current 6.03 branch
behave as version 4.xx, my tests show that the behavior is
effectively inadequate and inconsistent.

Although I had been previously nagging you in irc about maintaining
backward compatibility of the "force-prompt" keys, I have to ask you
to undo the aforementioned commit before the final release of 6.03
stable. The behavior of Syslinux 6.03 without this particular commit
will slightly "break" with the prior "force-prompt" behavior as seen
in 4.xx when using [vesa]menu.c32, but it will be more consistent and
clean.

Without this commit, the user can still avoid the automatic launch of
the default label by the same means (the "escape" "shift" keys),
which is the most important characteristic of MENU SHIFTKEY.

Please consider this request before the release of 6.03 stable.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>