x86: irq: Fix bug in setting IOAPIC pin attributes

Commit 15a3c7cc "x86, irq: Introduce two helper functions
to support irqdomain map operation" breaks LPSS ACPI enumerated
devices.

On startup, IOAPIC driver preallocates IRQ descriptors and programs
IOAPIC pins with default level and polarity attributes for all legacy
IRQs. Later legacy IRQ users may fail to set IOAPIC pin attributes
if the requested attributes conflicts with the default IOAPIC pin
attributes. So change mp_irqdomain_map() to allow the first legacy IRQ
user to reprogram IOAPIC pin with different attributes.

Reported-and-tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1409118795-17046-1-git-send-email-jiang.liu@linux.intel.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>