[ARM] 3939/1: don't reset SA11x0 clock counter

Don't reset OSCR to zero as this prevents us from having a contiguous
time source. The value returned by sched_clock() is reset to zero in the
middle of the boot process otherwise, making CONFIG_PRINTK_TIME rather
messed up.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>