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

Apple PowerMac based machines

modulename: macio_asic.ko

configname: CONFIG_PPC_PMAC

Linux Kernel Configuration
└─>Apple PowerMac based machines
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
drivers/macintosh/

depends
CONFIG_PPC_MULTIPLATFORM

is selected by
CONFIG_HERMES