ARM: versatile: Remove dead sched_clock code

Now that there's a DT based sched_clock driver in
drivers/clocksource/timer-versatile.c and all the Arm reference
platforms are DT only, the non-DT versatile sched_clock code can be
removed.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200409221952.31287-1-robh@kernel.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>