splice01/tee01/utime: add kernel version check for NFS test

Tests splice01 tee01 pass on NFS since 2.6.32 at least,
and utime01/02/03 pass since 2.6.18 at least.

Signed-off-by: Xiong Zhou <xzhou@redhat.com>
Reviewed-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>