smb: smbdirect: introduce SMBDIRECT_DEBUG_ERR_PTR() helper

smb: smbdirect: introduce SMBDIRECT_DEBUG_ERR_PTR() helper

This can be used like this:

  int err = somefunc();
  pr_warn("err=%1pe\n", SMBDIRECT_DEBUG_ERR_PTR(err));

This will be used in the following fixes in order
to be prepared to identify real world problems
more easily.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Paulo Alcantara <pc@manguebit.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>