default or selected kernelversion does not have config value CONFIG_MFD_SMSC.
Result is shown for kernelversion 6.9.9

SMSC ECE1099 series chips

modulename: smsc-ece1099.ko

configname: CONFIG_MFD_SMSC

Linux Kernel Configuration
└─>Device Drivers
└─>Multifunction device drivers
└─>SMSC ECE1099 series chips
In linux kernel since version 3.1 (release Date: 2011-10-24)  
If you say yes here you get support for the
ece1099 chips from SMSC.

To compile this driver as a module, choose M here: the
module will be called smsc.

source code: