ARM: convert arm to arch_gettimeoffset()

Convert arm to use GENERIC_TIME via the arch_getoffset() infrastructure,
reducing the amount of arch specific code we need to maintain.

The arm architecture is the last arch that need to be converted.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 2db43a5..8a5e8e9 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -97,6 +97,7 @@
 
 config ARCH_AT91X40
 	bool "AT91x40"
+	select ARCH_USES_GETTIMEOFFSET
 
 endchoice