clk: Drop dm.h header file in clk-provider.h

This header file should not be included in other header files. Remove it
and use a forward declaration and un-inlining of dev_get_clk_ptr()
instead.

Fix up the kendryte header files to avoid build errors.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Sean Anderson <seanga2@gmail.com>