SPARC: Emulation of GRLIB IRQMP

This device exposes two parameters:
 - set_pil_in        (ptr) : A function to set the pil_in of the SPARC CPU
 - set_pil_in_opaque (ptr) : Opaque argument of the set_pil_in function

Emulation of GrLib devices is base on the GRLIB IP Core User's Manual:
http://www.gaisler.com/products/grlib/grip.pdf

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
