x86, realmode: Unbreak the ia64 build of drivers/acpi/sleep.c

x86, realmode: Unbreak the ia64 build of drivers/acpi/sleep.c

Revert usage of acpi_wakeup_address and move definition
to x86 architecture code in order to make compilation work
in ia64.

[jsakkine: tested compilation in ia64/x86-64 and added
proper commit message]

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Originally-by: H. Peter Anvin <hpa@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1338370421-27735-1-git-send-email-jarkko.sakkinen@intel.com
Cc: Tony Luck <tony.luck@intel.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>