clk: Bail out when calculating phase fails during clk registration

Bail out of clk registration if we fail to get the phase for a clk that
has a clk_ops::get_phase() callback. Print a warning too so that driver
authors can easily figure out that some clk is unable to read back phase
information at boot.

Cc: Douglas Anderson <dianders@chromium.org>
Cc: Heiko Stuebner <heiko@sntech.de>
Suggested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20200205232802.29184-5-sboyd@kernel.org
Acked-by: Jerome Brunet <jbrunet@baylibre.com>