generic-ipi: merge fix

fix merge fallout:

arch/x86/pci/amd_bus.c: In function ‘enable_pci_io_ecs':
arch/x86/pci/amd_bus.c:581: error: too many arguments to function ‘on_each_cpu'

Signed-off-by: Ingo Molnar <mingo@elte.hu>