default or selected kernelversion does not have config value CONFIG_IBM_NEW_EMAC_ZMII.
Result is shown for kernelversion 6.2.5

CONFIG_IBM_NEW_EMAC_ZMII (not configurable)

configname: CONFIG_IBM_NEW_EMAC_ZMII

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet (10 or 100Mbit)
└─>IBM_NEW_EMAC_ZMII
In linux kernel since version 2.6.24 (release Date: 2008-01-24)