[POWERPC] Update defconfigs

This updates all the defconfigs in arch/powerpc/configs except iseries
and ps3, which were updated by the preceding commits.

This mostly takes the defaults, except that I turned on tickless idle
and high-resolution timers for everything, and turned off instrumentation
support and "Fair group CPU scheduler" for the smaller/embedded platforms.

Signed-off-by: Paul Mackerras <paulus@samba.org>