cs1180 adc return float，提高精度

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

Application/bsp/cs1180.c

@@ -430,7 +430,7 @@ float cs1180_adc_sample(int *valide)
 	}else {
 		a = a&0x7FFFF;
 	}
-	return (int)(((float)a / _cs1180_gain));
+	return (((float)a / _cs1180_gain));
 }