avr32: use Kbuild infrastructure to handle the asm-generic headers

Use kbuild to add asm-generic headers that do nothing, also remove the arch
specific wrapper headers.

This only affects headers that do nothing but include the generic
equivalent. It does not touch any header that does a little more.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>