CONFIG_PPC_BESTCOMM_FEC is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

Bestcomm FEC tasks support

modulename: bestcomm-fec.ko

configname: CONFIG_PPC_BESTCOMM_FEC

Linux Kernel Configuration
└─>Bestcomm FEC tasks support
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
This option enables the support for the FEC tasks.

source code:
/arch/powerpc/sysdev/bestcomm/

is selected by
CONFIG_FEC_MPC52xx