openrisc: io: Add missing __iomem annotation to iounmap()

With C=1:

drivers/soc/renesas/rmobile-sysc.c:330:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void *addr @@ got void [noderef] __iomem *[assigned] base @@
drivers/soc/renesas/rmobile-sysc.c:330:33: sparse: expected void *addr
drivers/soc/renesas/rmobile-sysc.c:330:33: sparse: got void [noderef] __iomem *[assigned] base

Fix this by adding the missing __iomem annotation to iounmap().

Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Stafford Horne <[e-mail]>

arch/openrisc/include/asm/io.h

···
 void __iomem *ioremap(phys_addr_t offset, unsigned long size);
 
 #define iounmap iounmap
-extern void iounmap(void *addr);
+extern void iounmap(void __iomem *addr);
 
 #include <asm-generic/io.h>
 

arch/openrisc/mm/ioremap.c

···
 }
 EXPORT_SYMBOL(ioremap);
 
-void iounmap(void *addr)
+void iounmap(void __iomem *addr)
 {
 	/* If the page is from the fixmap pool then we just clear out
 	 * the fixmap mapping.