[SPARC64]: Stop using __do_IRQ().

Invoke the desc->handle_irq directly in the top-level dispatch,
just like other sophisticated ports.

This will allow us to decrease the cost of the MSI queue dispatch.

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

diff --cc arch/sparc64/Kconfig
Simple merge

diff --cc arch/sparc64/kernel/irq.c
Simple merge

diff --cc arch/sparc64/kernel/pci_msi.c
Simple merge