Revert "x86-64, modify_ldt: Make support for 16-bit segments a runtime option"

This reverts commit fa81511bb0bbb2b1aace3695ce869da9762624ff in
preparation of merging in the proper fix (espfix64).

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

diff --cc arch/x86/kernel/ldt.c
Simple merge

diff --cc arch/x86/vdso/vdso32-setup.c
Simple merge