ksmbd: fix error code in ndr_read_int32()

This is a failure path and it should return -EINVAL instead of success.
Otherwise it could result in the caller using uninitialized memory.

Fixes: 303fff2b ("ksmbd: add validation for ndr read/write functions")
Cc: stable@vger.kernel.org # v5.15
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>