x86: head_64.S - remove useless balign

Impact: cleanup

NEXT_PAGE already has 'balign' so no
need to keep this redundant one.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: heukelum@fastmail.fm
Signed-off-by: Ingo Molnar <mingo@elte.hu>