CONFIG_MIPS_PB1100 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

AMD Alchemy PB1100 board

configname: CONFIG_MIPS_PB1100

System type
└─>AMD Alchemy PB1100 board
In linux kernel since version 2.6.12  

is selected by
CONFIG_FB_AU1100