default or selected kernelversion does not have config value CONFIG_MCHP_LAN966X_PCI.
Result is shown for kernelversion 6.6.75

Microchip LAN966x PCIe Support

modulename: lan966x-pci.ko

configname: CONFIG_MCHP_LAN966X_PCI

Linux Kernel Configuration
└─>Device Drivers
└─>Misc devices
└─>PCI support
└─>Microchip LAN966x PCIe Support
In linux kernel since version 5.4.290 (release Date: 2025-02-01)  
This enables the support for the LAN966x PCIe device.

This is used to drive the LAN966x PCIe device from the host system
to which it is connected. The driver uses a device tree overlay to
load other drivers to support for LAN966x internal components.

Even if this driver does not depend on those other drivers, in order
to have a fully functional board, the following drivers are needed:
- fixed-clock (COMMON_CLK)
- lan966x-oic (LAN966X_OIC)
- lan966x-cpu-syscon (MFD_SYSCON)
- lan966x-switch-reset (RESET_MCHP_SPARX5)
- lan966x-pinctrl (PINCTRL_OCELOT)
- lan966x-serdes (PHY_LAN966X_SERDES)
- lan966x-miim (MDIO_MSCC_MIIM)
- lan966x-switch (LAN966X_SWITCH)

source code:
selects
CONFIG_OF
CONFIG_OF_OVERLAY
CONFIG_IRQ_DOMAIN

depends
CONFIG_PCI