ARM: 7269/1: mach-sa1100: fix sched_clock breakage

Fixed up a simple typo in the runtime sched_clock conversion
so we compile again.

Cc: Kristoffer Ericson <kristoffer.ericson@gmail.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>