OMAP: Fix IOMEM macro for assembly

Otherwise IOMEM calculations can fail.
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/include/mach/io.h

@@ -201,7 +201,7 @@
 #define OMAP2_IO_ADDRESS(pa)	IOMEM(__OMAP2_IO_ADDRESS(pa))
 
 #ifdef __ASSEMBLER__
-#define IOMEM(x)		x
+#define IOMEM(x)		(x)
 #else
 #define IOMEM(x)		((void __force __iomem *)(x))