Use a generic name for this kind of PLL

Correction in dts files are already done here:
commit 5eb26c60 ("ARM: STi: DT: Rename st_pll3200c32_407_c0_x into st_pll3200c32_cx_x")
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>