sparc64: Build cpu list and mondo block at top-level xcall_deliver().

sparc64: Build cpu list and mondo block at top-level xcall_deliver().

Then modify all of the xcall dispatch implementations get passed and
use this information.

Now all of the xcall dispatch implementations do not need to be mindful
of details such as "is current cpu in the list?" and "is cpu online?"

Signed-off-by: David S. Miller <davem@davemloft.net>