xtensa: fix type conversion in __get_user_size

8-byte access in __get_user_size converts pointer to temporary variable
to the type of original user pointer and then dereferences it, resulting
in the following sparse warning:

  sparse: warning: dereference of noderef expression

Instead dereference the original user pointer under the __typeof__ and
add indirection outside.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/uaccess.h

@@ -204,7 +204,7 @@ do {									\
 			retval = -EFAULT;				\
 			(x) = 0;					\
 		} else {						\
-			(x) = *(__force __typeof__((ptr)))&__x;		\
+			(x) = *(__force __typeof__(*(ptr)) *)&__x;	\
 		}							\
 		break;							\
 	}								\