clk: beautify Makefile

The list of common clock types was getting a bit unmanageable.  This
patch puts only one file on each line and reorders the object files
alphabetically.  Also a newline is added to separate the sections.

Reported-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Prashant Gaikwad <pgaikwad@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>