enable porta clk in gpio_init

Signed-off-by: huhui <huhui@sharkgulf.com>

Application/bsp/gpio.c

@@ -1,6 +1,7 @@
 #include "gpio.h"
 /* all pins used as gpio(input/output/irq) must be defined here */
 void gpio_init(void){
+	rcu_periph_clock_enable(RCU_GPIOA);
 	rcu_periph_clock_enable(RCU_GPIOB);
 	rcu_periph_clock_enable(RCU_GPIOC);
 	rcu_periph_clock_enable(RCU_GPIOF);