With ARCH=powerpc we assume the presence of a device tree, so we don't
require any support for the old bi_recs method of passing boot
parameters.  Likewise, we've never needed it for ppc64, but we still
had an include/asm-ppc64/bootinfo.h from which nothing was used.  This
patch removes that file, and all references to it in arch/ppc64 and
arch/powerpc.  A related, unused variable 'boot_mem_size' is also
removed from setup_32.c.  The bootinfo stuff remains in ARCH=ppc for
the time being.

Built and booted on Power5 (ARCH=ppc64 and ARCH=powerpc), built for
32-bit powermac (ARCH=powerpc and ARCH=ppc).
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>