PM: Drop generic_subsys_pm_ops

Since the PM core is now going to execute driver callbacks directly
if the corresponding subsystem callbacks are not present,
forward-only subsystem callbacks (i.e. such that only execute the
corresponding driver callbacks) are not necessary any more.  Thus
it is possible to remove generic_subsys_pm_ops, because the only
callback in there that is not forward-only, .runtime_idle, is not
really used by the only user of generic_subsys_pm_ops, which is
vio_bus_type.

However, the generic callback routines themselves cannot be removed
from generic_ops.c, because they are used individually by a number
of subsystems.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

include/linux/pm.h

@@ -300,19 +300,6 @@ const struct dev_pm_ops name = { \
 	SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
 }
 
-/*
- * Use this for subsystems (bus types, device types, device classes) that don't
- * need any special suspend/resume handling in addition to invoking the PM
- * callbacks provided by device drivers supporting both the system sleep PM and
- * runtime PM, make the pm member point to generic_subsys_pm_ops.
- */
-#ifdef CONFIG_PM
-extern struct dev_pm_ops generic_subsys_pm_ops;
-#define GENERIC_SUBSYS_PM_OPS	(&generic_subsys_pm_ops)
-#else
-#define GENERIC_SUBSYS_PM_OPS	NULL
-#endif
-
 /**
  * PM_EVENT_ messages
  *