clk: u300: Fix incorrect placement of __initconst

__initconst should be placed between the variable name and equal
sign for the variable to be placed in the intended section.

While at it also make 'u300_clk_lookup' static as it is used only
in this file.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>