This device exposes one parameter:
 - chardev (ptr) : Pointer to a qemu character device

Emulation of GrLib devices is base on the GRLIB IP Core User's Manual:
http://www.gaisler.com/products/grlib/grip.pdfSigned-off-by: NFabien Chouteau <chouteau@adacore.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>