Rationalize __init/__devinit attributes.  The noteworthy changes are
that
iosapic_system_init(),
iosapic_init(),
iosapic_register_platform_intr(), and
iosapic_override_isa_irq()
are __init (only called from ACPI __init functions), but
iosapic_lists[],
num_iosapic,
find_iosapic(),
register_intr(),
iosapic_register_intr(), and
acpi_register_irq()
are not because they may be used after init-time by modules.

More detailed analysis:

        iosapic_lists[], num_iosapic: normal, referenced by
                find_iosapic (normal)
                register_intr (normal)
                iosapic_init (__init)

        pcat_compat: __initdata, referenced by
                iosapic_system_init (__init)
                iosapic_init (__init)
                iosapic_parse_prt (__init)

        find_iosapic: normal, called by
                register_intr (normal)

        register_intr: normal, called by
                iosapic_register_intr (normal), called by
                        acpi_register_irq (normal), called by
                                modules (=> can't be __init or __devinit)
                iosapic_register_platform_intr (__init)
                iosapic_override_isa_irq (__init)
                iosapic_parse_prt (__init)

        iosapic_reassign_vector: __init, called by
                iosapic_register_platform_intr (__init), called by
                        acpi_parse_plat_int_src (__init)

        iosapic_system_init: __init, called by
                acpi_parse_madt (__init)

        iosapic_init: __init, called by
                acpi_parse_iosapic (__init)

        iosapic_register_platform_intr: __init, called by
                acpi_parse_plat_int_src (__init)

        iosapic_override_isa_irq: __init, called by
                acpi_parse_int_src_ovr (__init)
                iosapic_init (__init)

        fixup_vector: __init, called by
                iosapic_parse_prt (__init), called by
                        acpi_pci_irq_init (__init)