powerpc/8xx: Enable 8M hugepage support with HW assistance

HW assistance naturally supports 8M huge pages without
further modifications.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/tlb_nohash.c

@@ -97,6 +97,9 @@ struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
 		.shift	= 14,
 	},
 #endif
+	[MMU_PAGE_8M] = {
+		.shift	= 23,
+	},
 };
 #else
 struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {