Now that we create of_platform devices earlier on cell, we can make the
axon_msi driver an of_platform driver.  This makes the code cleaner in
several ways, and most importantly means we have a struct device.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>