PM: merge device power-management source files

This patch (as993) merges the suspend.c and resume.c files in
drivers/base/power into main.c, making some public symbols private.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>