parisc: qemu idle sleep support

commit 310d82784fb4d60c80569f5ca9f53a7f3bf1d477 upstream.

Add qemu idle sleep support when running under qemu with SeaBIOS PDC
firmware.

Like the power architecture we use the "or" assembler instructions,
which translate to nops on real hardware, to indicate that qemu shall
idle sleep.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>