x86, boot: Not need to check setup_header version for setup_data

That is for bootloaders.

setup_data is in setup_header, and bootloader is copying that from bzImage.
So for old bootloader should keep that as 0 already.

old kexec-tools till now for elf image set setup_data to 0, so it is ok.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-28-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>