This allows platforms to specify the rate of the SP804 clocksource via
the clk subsystem.  While ARM boards clock these at 1MHz, BCMRing also
has SP804 timers but are clocked at different rates.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>