default or selected kernelversion does not have config value CONFIG_AMD_XGBE_PHY.
Result is shown for kernelversion 5.4.229

Driver for the AMD 10GbE (amd-xgbe) PHYs

modulename: amd-xgbe-phy.ko

configname: CONFIG_AMD_XGBE_PHY

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>PHY Device support and infrastructure
└─>Driver for the AMD 10GbE (amd-xgbe) PHYs
In linux kernel since version 3.16 (release Date: 2014-08-03)  
Currently supports the AMD 10GbE PHY

source code:
drivers/net/phy/amd-xgbe-phy.c

is depended by
CONFIG_AMD_XGBE