clk: define LOG_CATEGORY for generic and ccf clocks

Define LOG_CATEGORY to allow filtering with log command
for generic clock and CCF clocks.

This patch also change existing printf, debug and pr_ macro
to log_ or dev_ macro.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>