clock: Move PLLU init/deinit from USB to clock

bdk/soc/clock.h

@@ -478,6 +478,8 @@ void clock_enable_pwm();
 void clock_disable_pwm();
 void clock_enable_pllc(u32 divn);
 void clock_disable_pllc();
+void clock_enable_pllu();
+void clock_disable_pllu();
 void clock_sdmmc_config_clock_source(u32 *pclock, u32 id, u32 val);
 void clock_sdmmc_get_card_clock_div(u32 *pclock, u16 *pdivisor, u32 type);
 int  clock_sdmmc_is_not_reset_and_enabled(u32 id);