x86: Add missing bzImage fields to struct setup_header

commit 37ba7ab5e33c ("x86, boot: make kernel_alignment adjustable; new
bzImage fields") introduced some new fields into the bzImage header
but struct setup_header was not updated accordingly. Add the missing
'pref_address' and 'init_size' fields.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1318848017-12301-1-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>