net: fec_ptp: fix issue caused by refactor the fec_devtype

Commit da722186 ("net: fec: set GPR bit on suspend by DT configuration.")
refactor the fec_devtype, need adjust ptp driver accordingly.

Fixes: da722186 ("net: fec: set GPR bit on suspend by DT configuration.")
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>