libexternal: Support VESA format

Add support for VESA formats with pixel clock
at 65MHz. This change helps verify support
for formats corresponding to 65MHz in the
HDMI/MHL driver by using 1024x768p604:3 resolution.

Change-Id: I28b4adcfced7e8bfe7b75c534f5b15c25138ef7f

libexternal/external.cpp

@@ -746,6 +746,11 @@ void ExternalDisplay::getAttrForMode(int& width, int& height, int& fps) {
             height = 1024;
             fps = 60;
             break;
+        case HDMI_VFRMT_1024x768p60_4_3:
+            width = 1024;
+            height = 768;
+            fps = 60;
+            break;
         case HDMI_VFRMT_1920x1080p24_16_9:
             width = 1920;
             height = 1080;