sparc64: Fix UP bootup regression.

Commit b696fdc2 ("sparc64: Defer
cpu_data() setup until end of per-cpu data initialization.") broke
bootup for UP builds because the cpu_data() initialization only
occurs in setup_per_cpu_areas() which is never compiled in nor
called in UP builds.

Fix this up by calling the setups directly from init_64.c when
non-SMP.

Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Tested-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>