[ARM] 3926/1: make timer led handle HZ != 100

The timer LED is unusable at HZ=large, since it's got
a hard-wired value of 100 ticks per cycle; when HZ=1024
(for example) it's essentially always-on.  This patch
just makes that be HZ ticks per cycle.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>