Fix build problem on ARM ... the only user of "rtc_lock" today is the
optional PC-style "CMOS" RTC driver, not the legacy SA1100 RTC driver.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

Index: at91/arch/arm/kernel/time.c
===================================================================
--- at91.orig/arch/arm/kernel/time.c	2006-11-10 09:47:46.000000000 -0800
+++ at91/arch/arm/kernel/time.c	2007-01-09 15:08:39.000000000 -0800
@@ -38,12 +38,14 @@
  */
 struct sys_timer *system_timer;
 
+#if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE)
 /* this needs a better home */
 DEFINE_SPINLOCK(rtc_lock);
 
-#ifdef CONFIG_SA1100_RTC_MODULE
+#ifdef CONFIG_RTC_DRV_CMOS_MODULE
 EXPORT_SYMBOL(rtc_lock);
 #endif
+#endif	/* pc-style 'CMOS' RTC support */
 
 /* change this if you have some constant time drift */
 #define USECS_PER_JIFFY	(1000000/HZ)