[ARM] 3855/1: Add generic time support

This patch adds Generic time-of-day support for the ARM architecture.

The support is currently added using #ifdef's so that it can support
sub-arches that do not (yet) have a clocksource added.  As sub-arches
add clocksource support, they should 'select GENERIC_TIME'

Signed-off-by: Deepak Saxena <dsaxena@mvista.com>
Signed-off-by: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Kevin Hilman <khilman@mvista.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>