clk: versatile: delete old RealView clock implementation

The old RealView clock implementation is not used anymore
(nothing in the kernel calls realview_clk_init()) as we have
moved all clocks over to device tree. Delete it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>