drivers: sh: pm_runtime does not need idle callback

In the runtime_pm idle callback the code assumes that a NULL .runtime_idle
entry is the same as a .runtime_idle entry that returns 0 as a result. This
means the entry in drivers/sh/pm_runtime can be removed in favour of just
leaving the entry NULL.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> [r8a7779 legacy]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

drivers/sh/pm_runtime.c

@@ -21,18 +21,10 @@
 #include <linux/slab.h>
 
 #ifdef CONFIG_PM_RUNTIME
-
-static int default_platform_runtime_idle(struct device *dev)
-{
-	/* suspend synchronously to disable clocks immediately */
-	return 0;
-}
-
 static struct dev_pm_domain default_pm_domain = {
 	.ops = {
 		.runtime_suspend = pm_clk_suspend,
 		.runtime_resume = pm_clk_resume,
-		.runtime_idle = default_platform_runtime_idle,
 		USE_PLATFORM_PM_SLEEP_OPS
 	},
 };