kernel: Apply the SUSFS patch

kernel/kernel_umount.h

@@ -6,6 +6,10 @@
 void ksu_kernel_umount_init(void);
 void ksu_kernel_umount_exit(void);
 
+#ifdef CONFIG_KSU_SUSFS_TRY_UMOUNT
+void susfs_try_umount_all(uid_t uid);
+#endif
+
 // Handler function to be called from setresuid hook
 int ksu_handle_umount(uid_t old_uid, uid_t new_uid);