dpaa2-ptp: fix compile error

phylink_set_port_modes will be compiled if CONFIG_PHYLINK enabled,
dpaa2_mac_validate will be compiled if CONFIG_FSL_DPAA2_ETH enabled,
it should select CONFIG_PHYLINK when dpaa2_mac_validate call
phylink_set_port_modes

drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.o: In function `dpaa2_mac_validate':
dpaa2-mac.c:(.text+0x3a1): undefined reference to `phylink_set_port_modes'
drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.o: In function `dpaa2_mac_connect':
dpaa2-mac.c:(.text+0x91a): undefined reference to `phylink_create'
dpaa2-mac.c:(.text+0x94e): undefined reference to `phylink_of_phy_connect'
dpaa2-mac.c:(.text+0x97f): undefined reference to `phylink_destroy'
drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.o: In function `dpaa2_mac_disconnect':
dpaa2-mac.c:(.text+0xa9f): undefined reference to `phylink_disconnect_phy'
dpaa2-mac.c:(.text+0xab0): undefined reference to `phylink_destroy'
make: *** [vmlinux] Error 1

Fixes: 71947923 ("dpaa2-eth: add MAC/PHY support through phylink")
Signed-off-by: Chenwandun <chenwandun@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>