ARM: OMAP2+: clock/interface: remove some headers from clkt_iclk.c file

Instead, copy the used constants from the header file to the source file.
This allows the code to be migrated under drivers folder where we don't
have access to the OMAP specific header files.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Paul Walmsley <paul@pwsan.com>