sparc64: Fix sparse warnings in pci.c

sparc64: Fix sparse warnings in pci.c

1) Declare pci_poke_* in pci_impl.h
2) of_create_pci_dev() should be static
3) ->setup_msi_irq() wants an unsigned int pointer not a plain
   int one
4) void value expression return in arch_teardown_msi_irq()

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