Fill in the appropriate limits to avoid inconsistencies
in the vfs cached inode times when timestamps are
outside the permitted range.

Also fixed cnvrtDosUnixTm calculations to avoid int overflow
while computing maximum date.

References:

http://cifs.com/

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-cifs/d416ff7c-c536-406e-a951-4f04b2fd1d2bSigned-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Cc: sfrench@samba.org
Cc: linux-cifs@vger.kernel.org