powerpc/powernv: Build a zImage.epapr

The zImage.epapr wrapper allows to use zImages when booting via a flat
device-tree which can be used on powernv.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/powernv/Kconfig

@@ -6,6 +6,7 @@ config PPC_POWERNV
 	select PPC_ICP_NATIVE
 	select PPC_P7_NAP
 	select PPC_PCI_CHOICE if EMBEDDED
+	select EPAPR_BOOT
 	default y
 
 config POWERNV_MSI