x86/asm/suspend: Get rid of bogus_64_magic

bogus_64_magic is only a dead-end loop. There is no need for an
out-of-order function (and unannotated local label), so just handle it
in-place and also store 0xbad-m-a-g-i-c to %rcx beforehand, in case
someone is inspecting registers.

Here a qemu+gdb example:

  Remote debugging using localhost:1235
  wakeup_long64 () at arch/x86/kernel/acpi/wakeup_64.S:26
  26              jmp 1b
  (gdb) info registers
  rax            0x123456789abcdef0       1311768467463790320
  rbx            0x0      0
  rcx            0xbad6d61676963  3286910041024867
  		 ^^^^^^^^^^^^^^^

 [ bp: Add the gdb example. ]

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190906075550.23435-1-jslaby@suse.cz