Ftgmac100's checksum issue has been fixed by commit 88824e3bf29a ("net:
ethernet: ftgmac100: Fix DMA coherency issue with SW checksum") so this
property is no longer required.
Signed-off-by: Tao Ren <rentao.bupt@gmail.com> Signed-off-by: Joel Stanley <joel@jms.id.au>