parisc: Use __ro_after_init in drivers.c

Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/kernel/drivers.c

@@ -41,7 +41,7 @@
 #include <asm/ropes.h>
 
 /* See comments in include/asm-parisc/pci.h */
-const struct dma_map_ops *hppa_dma_ops __read_mostly;
+const struct dma_map_ops *hppa_dma_ops __ro_after_init;
 EXPORT_SYMBOL(hppa_dma_ops);
 
 static struct device root = {