ARM: add permission annotations to MT_MEMORY* mapping types

Document the permissions which the various MT_MEMORY* mapping types
will provide.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
index cd22262..07b68d5 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -244,7 +244,7 @@
 		.virtual	= OMAP4_SRAM_VA,
 		.pfn		= __phys_to_pfn(OMAP4_SRAM_PA),
 		.length		= PAGE_SIZE,
-		.type		= MT_MEMORY_SO,
+		.type		= MT_MEMORY_RW_SO,
 	},
 #endif
 
@@ -282,7 +282,7 @@
 		.virtual	= OMAP4_SRAM_VA,
 		.pfn		= __phys_to_pfn(OMAP4_SRAM_PA),
 		.length		= PAGE_SIZE,
-		.type		= MT_MEMORY_SO,
+		.type		= MT_MEMORY_RW_SO,
 	},
 #endif
 };