microblaze: fix __get_user()

Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

arch/microblaze/include/asm/uaccess.h

@@ -227,7 +227,7 @@ extern long __user_bad(void);
 
 #define __get_user(x, ptr)						\
 ({									\
-	unsigned long __gu_val;						\
+	unsigned long __gu_val = 0;					\
 	/*unsigned long __gu_ptr = (unsigned long)(ptr);*/		\
 	long __gu_err;							\
 	switch (sizeof(*(ptr))) {					\