x86: Make EFI RTC function depend on 32bit again

The EFI RTC functions are only available on 32 bit. commit 7bd867df
(x86: Move get/set_wallclock to x86_platform_ops) removed the 32bit
dependency which leads to boot crashes on 64bit EFI systems.

Add the dependency back. 
Solves: http://bugzilla.kernel.org/show_bug.cgi?id=14466

Tested-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Feng Tang <feng.tang@intel.com>
LKML-Reference: <20091020125402.028d66d5@feng-desktop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/efi.c

@@ -454,8 +454,10 @@ void __init efi_init(void)
 	if (add_efi_memmap)
 		do_add_efi_memmap();
 
+#ifdef CONFIG_X86_32
 	x86_platform.get_wallclock = efi_get_time;
 	x86_platform.set_wallclock = efi_set_rtc_mmss;
+#endif
 
 	/* Setup for EFI runtime service */
 	reboot_type = BOOT_EFI;