AVR32: Define PAGE_SHARED

The virtual framebuffer driver needs PAGE_SHARED, which is not defined
on avr32. Define it.

Reported-by: Oliver Zander <ozander@como.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/include/asm-avr32/pgtable.h b/include/asm-avr32/pgtable.h
index 018f6e2..3ae7b54 100644
--- a/include/asm-avr32/pgtable.h
+++ b/include/asm-avr32/pgtable.h
@@ -157,6 +157,7 @@
 #define _PAGE_S(x)	_PAGE_NORMAL(x)
 
 #define PAGE_COPY	_PAGE_P(PAGE_WRITE | PAGE_READ)
+#define PAGE_SHARED	_PAGE_S(PAGE_WRITE | PAGE_READ)
 
 #ifndef __ASSEMBLY__
 /*