update lib to latest, and fix for changes

rcc_core_frequency -> rcc_ahb_frequency

examples/stm32/f0/stm32f0-discovery/systick_blink/systick_blink.c

@@ -37,7 +37,7 @@ static void systick_setup(int freq)
 	/* clear counter so it starts right away */
 	STK_CVR = 0;
 
-	systick_set_reload(rcc_core_frequency / freq);
+	systick_set_reload(rcc_ahb_frequency / freq);
 	systick_counter_enable();
 	systick_interrupt_enable();
 }