drivers: clk: st: Correct the pll-type for A9 for stih418

Add support for new PLL-type for stih418 A9-PLL.
Currently the 407_A9_PLL type being used, it is corrected with this patch
4600c28 PLL allows to reach higher frequencies
so its programming algorithm is extended.

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