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

Maple 970FX Evaluation Board

modulename: udbg_16550.ko

configname: CONFIG_PPC_MAPLE

Linux/PowerPC Kernel Configuration
└─>Platform support
└─> Maple 970FX Evaluation Board
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
This option enables support for the Maple 970FX Evaluation Board.
For more informations, refer to <http://www.970eval.com>

source code:
arch/powerpc/kernel/udbg_16550.c