[bsp][ch32]pwm避免警告 (#6818)

bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.c

@@ -17,6 +17,8 @@
 #define LOG_TAG "drv.pwm"
 #include <drv_log.h>
 
+#define ITEM_NUM(items) sizeof(items) / sizeof(items[0])
+
 void ch32_tim_clock_init(TIM_TypeDef* timx)
 {
 #ifdef BSP_USING_TIM1_PWM

bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.h

@@ -18,10 +18,6 @@
 #include <drivers/hwtimer.h>
 #include <board.h>
 
-#ifndef ITEM_NUM
-#define ITEM_NUM(items) sizeof(items) / sizeof(items[0])
-#endif
-
 #define MAX_COUNTER     65535
 #define MIN_COUNTER     2
 #define MIN_PULSE       2