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

PCI Express Bandwidth Change Notification

modulename: bw_notification.ko

configname: CONFIG_PCIE_BW

Linux Kernel Configuration
└─>Device Drivers
└─>PCI support
└─>PCI Express Bandwidth Change Notification
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This enables PCI Express Bandwidth Change Notification. If
you know link width or rate changes occur only to correct
unreliable links, you may answer Y.

source code:
drivers/pci/pcie/bw_notification.c