x86: fix Section mismatch: reference to .init.text:lguest_entry

fix:

> WARNING: vmlinux.o(.data+0x4): Section mismatch: reference to .init.text:lguest_entry (between 'subarch_entries' and 'stack_start')

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>