[bsp][CV1800B] fix cv1800b polarity reversal error

Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@gmail.com>

bsp/cvitek/drivers/drv_pwm.c

@@ -31,7 +31,7 @@ static void cvi_pwm_set_config(rt_ubase_t reg_base, struct rt_pwm_configuration
 {
     unsigned long long duty_clk, period_clk;
 
-    cvi_pwm_set_polarity_low_ch(reg_base, (cfg->channel & PWM_MAX_CH));
+    cvi_pwm_set_polarity_high_ch(reg_base, (cfg->channel & PWM_MAX_CH));
 
     duty_clk = (cfg->pulse * count_unit) / NSEC_COUNT;
     cvi_pwm_set_high_period_ch(reg_base, (cfg->channel & PWM_MAX_CH), duty_clk);