powerpc/powernv: Fix missing Kconfig dependency for MSIs

We need PPC_MSI_BITMAP support

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/sysdev/Kconfig b/arch/powerpc/sysdev/Kconfig
index a84fecf..8223f78 100644
--- a/arch/powerpc/sysdev/Kconfig
+++ b/arch/powerpc/sysdev/Kconfig
@@ -19,6 +19,7 @@
 	default y if MPIC
 	default y if FSL_PCI
 	default y if PPC4xx_MSI
+	default y if PPC_POWERNV
 
 source "arch/powerpc/sysdev/xics/Kconfig"