powerpc/e500/qemu-e500: allow core to idle without waiting

This means an idle guest won't needlessly consume an entire core on
the host, waiting for work to show up.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Acked-by: Scott Wood <oss@buserror.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220112112459.1033754-1-troglobit@gmail.com

arch/powerpc/platforms/85xx/qemu_e500.c

@@ -67,4 +67,9 @@ define_machine(qemu_e500) {
 	.get_irq		= mpic_get_coreint_irq,
 	.calibrate_decr		= generic_calibrate_decr,
 	.progress		= udbg_progress,
+#ifdef CONFIG_PPC64
+	.power_save		= book3e_idle,
+#else
+	.power_save		= e500_idle,
+#endif
 };