default or selected kernelversion does not have config value CONFIG_PCI_MT7621_PHY.
Result is shown for kernelversion 6.9.8

MediaTek MT7621 PCI PHY Driver

modulename: pci-mt7621-phy.ko

configname: CONFIG_PCI_MT7621_PHY

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>Device Tree and Open Firmware support
└─>MediaTek MT7621 PCI PHY Driver
In linux kernel since version 5.1 (release Date: 2019-05-05)  
Say 'Y' here to add support for MediaTek MT7621 PCI PHY driver,

source code:
drivers/staging/mt7621-pci-phy/pci-mt7621-phy.c