kbuild, suspend, x86: fix rebuild of wakeup.bin

In kernel/acpi/realmode/Makefile use the 'always'
variable to say that wakeup.bin should always
be made.

In acpi/Makefile we then do not need to specify the
requested target and we avoid the message from make:

   `arch/x86/kernel/acpi/realmode/wakeup.bin' is up to date.

Add wakeup.lds to list af targets to avoid rebuilding
wakeup.bin - from Roland McGrath.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@suse.cz>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>