x86, realmode: don't copy real_mode_header

Replaced copying of real_mode_header with a pointer
to beginning of RM memory.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-19-git-send-email-jarkko.sakkinen@intel.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>