clk: Add missing stubs for a few functions

Compilation fails if any of undeclared clk_set_*() functions are in use
and CONFIG_HAVE_CLK=n.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>