Some servers such as Windows 10 will return STATUS_INSUFFICIENT_RESOURCES
as the number of simultaneous SMB3 requests grows (even though the client
has sufficient credits).  Return EAGAIN on STATUS_INSUFFICIENT_RESOURCES
so that we can retry writes which fail with this status code.

This (for example) fixes large file copies to Windows 10 on fast networks.

Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>