powerpc/cell: Fix Axon MSI driver dependencies

The Axon MSI driver depends on more than just PCI_MSI, so add a
Kconfig fragment for it. Fixes randconfig build failures.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/cell/Kconfig

@@ -43,6 +43,11 @@ config PPC_CELL_QPACE
 	depends on PPC_MULTIPLATFORM && PPC64
 	select PPC_CELL_COMMON
 
+config AXON_MSI
+	bool
+	depends on PPC_IBM_CELL_BLADE && PCI_MSI
+	default y
+
 menu "Cell Broadband Engine options"
 	depends on PPC_CELL
 

arch/powerpc/platforms/cell/Makefile

@@ -28,7 +28,7 @@ obj-$(CONFIG_SPU_BASE)			+= spu_callbacks.o spu_base.o \
 					   $(spu-manage-y) \
 					   spufs/
 
-obj-$(CONFIG_PCI_MSI)			+= axon_msi.o
+obj-$(CONFIG_AXON_MSI)			+= axon_msi.o
 
 # qpace setup
 obj-$(CONFIG_PPC_CELL_QPACE)		+= qpace_setup.o