clk: stm32f4: Use CLK_OF_DECLARE_DRIVER initialization method

Clock and reset controller use same compatible strings (same IP).

Since commit 989eafd0

 ("clk: core: Avoid double initialization of
clocks") the OF core flags clock controllers registered with the
CLK_OF_DECLARE() macro as OF_POPULATED, so platform devices with the same
compatible string will not be registered.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>