arm64/uaccess: fix sparse errors

virtio wants to read bitwise types from userspace using get_user.  At the
moment this triggers sparse errors, since the value is passed through an
integer.

Fix that up using __force.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 3bf8f4e..9a2069b 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -147,7 +147,7 @@
 	default:							\
 		BUILD_BUG();						\
 	}								\
-	(x) = (__typeof__(*(ptr)))__gu_val;				\
+	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
 } while (0)
 
 #define __get_user(x, ptr)						\