From: "Martin J. Bligh" <mbligh@aracnet.com>

The "magic" switching in subarch was ugly when I put it there, and nobody
liked it then (including me).  It hasn't got any prettier since.  Andi's
generic arch stuff is a cleaner solution for now, so we can remove the old
hacky stuff, and significantly simplify the code.  All this does is replace
"(x86_summit ?  A : B)" with "A" everywhere.