The default PSW is set by the operating system with the PDC_PSW
firmware call.  Use that setting to decide if wide mode is to be
enabled for interruptions and EIRR usage.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>