linuxkpi: Add xa_insert_irq wrapper

[jhb]

Summary

This just invokes xa_insert similar to other xa_*_irq wrappers.

Sponsored by: Chelsio Communications

[bz]

For what it's there it is fine.

I believe 5542309ec6eba3af9e26c50acd654de462181b8e from @dumbbell and yours up there needs to be revised as the *_irq versions should hold that xa_lock_irq and unlock around the middle call but it may be better to do this in a follow-up pass.