CH34x: for baud rate 307200 use special divisor+factor with lower deviation

.idea/markdown.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="MarkdownSettings">
+    <option name="previewPanelProviderInfo">
+      <ProviderInfo name="Compose (experimental)" className="com.intellij.markdown.compose.preview.ComposePanelProvider" />
+    </option>
+  </component>
+</project>

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/Ch34xSerialDriver.java

@@ -199,6 +199,9 @@ public class Ch34xSerialDriver implements UsbSerialDriver {
             if (baudRate == 921600) {
                 divisor = 7;
                 factor = 0xf300;
+            } else if (baudRate == 307200) {
+                divisor = 7;
+                factor = 0xd900;
             } else {
                 final long BAUDBASE_FACTOR = 1532620800;
                 final int BAUDBASE_DIVMAX = 3;