of/irq: move of_msi_configure to the right guard and add a dummy

of_msi_configure is part of of_irq.c, which is compiled in when OF_IRQ
is enabled, not just OF.
Also It is unconditionally called from of_platform_device_create_pdata,
which does not depend on OF_IRQ, just OF_ADDRESS, so we need a dummy
implementation in case of OF_ADDRESS=y but OF_IRQ=n.

Fixes: c706c239 ("of/platform: Assign MSI domain to platform device")
Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Signed-off-by: Rob Herring <robh@kernel.org>