Stop including dev/pci/files.ath in arch/i386/conf/files.i386,
since we get the same definitions by including dev/pci/files.pci,
now. Remove dev/pci/files.ath.
Add arch/macppc/conf/Makefile.macppc with directives for linking
the Atheros HAL for PowerPC.
In athhal-powerpc-be-eabi.opt_ah.h, #define AH_REGOPS_FUNC 1, since
otherwise the linker complains that the PowerPC HAL cannot link
with register-read/write subroutines.
Add ath(4) to the GENERIC macppc kernel configuration; comment it
out.