fs: nfs: Initialize filesystem timestamp ranges

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

The time formats for various verious is detailed in the
RFCs as below:

https://tools.ietf.org/html/rfc7862(time metadata)
https://tools.ietf.org/html/rfc7530:

nfstime4

   struct nfstime4 {
           int64_t         seconds;
           uint32_t        nseconds;
   };

https://tools.ietf.org/html/rfc1094

          struct timeval {
              unsigned int seconds;
              unsigned int useconds;
          };

https://tools.ietf.org/html/rfc1813



struct nfstime3 {
         uint32   seconds;
         uint32   nseconds;
      };

Use the limits as per the RFC.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Cc: trond.myklebust@hammerspace.com
Cc: anna.schumaker@netapp.com
Cc: linux-nfs@vger.kernel.org