snapshot-switch --must-restore: fix restoring config

A weird typo in commit 6be5c58, found by coverity:

> CID 1256610 (#1 of 1): Incorrect sizeof expression (BAD_SIZEOF)
> bad_sizeof: Taking the size of pointer arithmetic expression
> ve_conf_old - 4 is suspicious.
>
> Did you intend sizeof (ve_conf_old) - 4?

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed