target/ppc: pass const string to kvmppc_is_mem_backend_page_size_ok()

This function has three implementations. Two are stubs that do nothing
and the third one only passes the obj_path argument to:

Object *object_resolve_path(const char *path, bool *ambiguous);

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
index f48243d..eab7c8f 100644
--- a/target/ppc/kvm_ppc.h
+++ b/target/ppc/kvm_ppc.h
@@ -64,7 +64,7 @@
 int kvmppc_put_books_sregs(PowerPCCPU *cpu);
 PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void);
 
-bool kvmppc_is_mem_backend_page_size_ok(char *obj_path);
+bool kvmppc_is_mem_backend_page_size_ok(const char *obj_path);
 
 #else
 
@@ -211,7 +211,7 @@
     return ram_size;
 }
 
-static inline bool kvmppc_is_mem_backend_page_size_ok(char *obj_path)
+static inline bool kvmppc_is_mem_backend_page_size_ok(const char *obj_path)
 {
     return true;
 }