x86/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: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/uaccess.h

@@ -179,7 +179,7 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 	asm volatile("call __get_user_%P3"				\
 		     : "=a" (__ret_gu), "=r" (__val_gu)			\
 		     : "0" (ptr), "i" (sizeof(*(ptr))));		\
-	(x) = (__typeof__(*(ptr))) __val_gu;				\
+	(x) = (__force __typeof__(*(ptr))) __val_gu;			\
 	__ret_gu;							\
 })