CONFIG_BOOTLOADER_FAMILY is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
default or selected kernelversion does not have config value CONFIG_BOOTLOADER_FAMILY.
Result is shown for kernelversion 6.2.5

POWERTV Bootloader Family string

configname: CONFIG_BOOTLOADER_FAMILY

Linux Kernel Configuration
└─>POWERTV Bootloader Family string
In linux kernel since version 2.6.33 (release Date: 2010-02-24)  
This value should be specified when the bootloader driver is disabled
and must be exactly two characters long. Families supported are:
R1 - RNG-100 R2 - RNG-200
A1 - Class A B1 - Class B
E1 - Class E F1 - Class F
44 - 45xx 46 - 46xx
85 - 85xx 86 - 86xx