arm64: Remove shadowed asm-generic headers

We've grown our own versions of bug.h, ftrace.h, pci.h and topology.h,
so generating the generic ones as well is unnecessary and a potential
source of build hiccups. At the very least, having them present has
confused my source-indexing tool, and that simply will not do.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>