SMB3: Allow persistent handle timeout to be configurable on mount

Reconnecting after server or network failure can be improved
(to maintain availability and protect data integrity) by allowing
the client to choose the default persistent (or resilient)
handle timeout in some use cases.  Today we default to 0 which lets
the server pick the default timeout (usually 120 seconds) but this
can be problematic for some workloads.  Add the new mount parameter
to cifs.ko for SMB3 mounts "handletimeout" which enables the user
to override the default handle timeout for persistent (mount
option "persistenthandles") or resilient handles (mount option
"resilienthandles").  Maximum allowed is 16 minutes (960000 ms).
Units for the timeout are expressed in milliseconds. See
section 2.2.14.2.12 and 2.2.31.3 of the MS-SMB2 protocol
specification for more information.

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