staging: tidspbridge: Prepare for irqs.h removal

Let's define some things locally to avoid breaking build
when irqs.h is removed.

This is needed for the ARM common zImage support.

Cc: Omar Ramirez Luna <omar.ramirez@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>