xen:events: move find_unbound_irq inside CONFIG_PCI_MSI
xen:events: move find_unbound_irq inside CONFIG_PCI_MSI

The only caller is xen_allocate_pirq_msi which is also under this
ifdef so this fixes:
    drivers/xen/events.c:377: warning: 'find_unbound_pirq' defined but not used
when CONFIG_PCI_MSI=n

Signed-off-by: Ian Campbell <9be92b3dbbd6611e3e4c9209fb3d04b4919e7cca@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <da3a51b335cef0eb0e2c329c5ef6bcd6acef687a@oracle.com>
Cc: Stefano Stabellini <22a0c6385d750d07aa383c9f813cf6f0228657d8@eu.citrix.com>
Cc: Jeremy Fitzhardinge <b3f594e10a9edcf5413cf1190121d45078c62290@goop.org>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs