perf/hw_breakpoint: Remove arch breakpoint hooks

PowerPC was the only user of these hooks, and has been refactored to no
longer require them. There is no need to keep them around, so remove
them to reduce complexity.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-8-bgray@linux.ibm.com