PM / wakeirq: Avoid setting power.wakeirq too hastily

If dev_pm_attach_wake_irq() fails, the device's power.wakeirq field
should not be set to point to the struct wake_irq passed to that
function, as that object will be freed going forward.

For this reason, make dev_pm_attach_wake_irq() first call
device_wakeup_attach_irq() and only set the device's power.wakeirq
field if that's successful.

That requires device_wakeup_attach_irq() to be called under the
device's power.lock lock, but since dev_pm_attach_wake_irq() is
the only caller of it, the requisite changes are easy to make.

Fixes: 4990d4fe (PM / Wakeirq: Add automated device wake IRQ handling)
Reported-by: Felipe Balbi <balbi@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>