treewide: Move CONFIG_PHY_MARVELL to Kconfig

The CONFIG_PHY_MARVELL has already been migrated to Kconfig (some boards
already had it in their Kconfig), but had not been moved for older
boards.

Move it to the defconfigs for all boards.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/configs/MPC8541CDS_legacy_defconfig b/configs/MPC8541CDS_legacy_defconfig
index 7eb5846..605d2b4 100644
--- a/configs/MPC8541CDS_legacy_defconfig
+++ b/configs/MPC8541CDS_legacy_defconfig
@@ -18,6 +18,7 @@
 CONFIG_ENV_IS_IN_FLASH=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
+CONFIG_PHY_MARVELL=y
 CONFIG_NETDEVICES=y
 CONFIG_TSEC_ENET=y
 CONFIG_CONS_INDEX=2