[PATCH] Remove unneeded #defines in head.S

arch/ppc64/kernel/head.S #defines SECONDARY_PROCESSORS then has some
#ifdefs based on it.  Whatever purpose this had is long lost, this
patch removes it.

Likewise, head.S defines H_SET_ASR, which is now defined, along with
other hypervisor call numbers in hvcall.h.  This patch deletes it, as
well, from head.S.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>