lasi: use numerical constant for iar reset value

lasi: use numerical constant for iar reset value

This is to allow us to decouple the LASI device from the board logic. If it is
decided later that this value needs to be configurable then it can easily be
converted to a qdev property.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Acked-by: Helge Deller <deller@gmx.de>
Message-Id: <20220504092600.10048-41-mark.cave-ayland@ilande.co.uk>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>