serial: core: delete .set_wake() callback

This deletes the .set_wake() callback in the struct uart_ops.
Apparently this has been unused since pre-git times. In the
old-2.6-bkcvs it is deleted as part of a changeset removing
the PM_SET_WAKEUP from pm_request_t which is since also deleted
from the kernel.

The apropriate way to set wakeups in the kernel is to have a
code snippet like this in .suspend() or .runtime_suspend()
callbacks:

static int foo_suspend(struct device *dev)
{
if (device_may_wakeup(dev)) {
/* Enable wakeups, set internal states */
}
}

This specific callback is not coming back.

Cc: Rafael J. Wysocki <[e-mail]>
Cc: Len Brown <[e-mail]>
Cc: Pavel Machek <[e-mail]>
Cc: Kevin Hilman <[e-mail]>
Cc: Dmitry Artamonow <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/serial/driver

···
 	Locking: none.
 	Interrupts: caller dependent.
 
-  set_wake(port,state)
-	Enable/disable power management wakeup on serial activity.  Not
-	currently implemented.
-
   type(port)
 	Return a pointer to a string constant describing the specified
 	port, or return NULL, in which case the string 'unknown' is

include/linux/serial_core.h

···
 	void		(*set_ldisc)(struct uart_port *, int new);
 	void		(*pm)(struct uart_port *, unsigned int state,
 			      unsigned int oldstate);
-	int		(*set_wake)(struct uart_port *, unsigned int state);
 
 	/*
 	 * Return a string describing the type of the port