of: MSI: Simplify irqdomain lookup

of: MSI: Simplify irqdomain lookup

So far, when trying to associate a device with its MSI domain,
we first lookup the domain using a MSI token, and if this
doesn't return anything useful, we pick up any domain matching
the same node.

This logic is broken for two reasons:
1) Only the generic MSI code (PCI or platform) sets this token
   to PCI/MSI or platform MSI. So we're guaranteed that if there
   is something to be found, we will find it with the first call.
2) If we have a convoluted situation where:
   - a single node implements both wired and MSI interrupts
   - MSI support for that HW hasn't been compiled in
   we'll end up using the wired domain for MSIs anyway, and things
   break badly.

So let's just remove __of_get_msi_domain, and replace it by a direct
call to irq_find_matching_host, because that's what we really want.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Rob Herring <robh+dt@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1453816347-32720-3-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>