Add another Mega2560 Board, with CP2012

This patch adds the PID/VID for my "KS0499 Mega 2560 Plus Board" (keyestudio). It is a mega2560,  with has the CP2012 as USB interface.
For more Information, see  https://wiki.keyestudio.com/KS0499_KEYESTUDIO_Mega_2560_Plus_Board

Author: softhack007

boards.txt

@@ -233,6 +233,8 @@ mega.vid.4=0x2341
 mega.pid.4=0x0210
 mega.vid.5=0x2341
 mega.pid.5=0x0242
+mega.vid.6=0x10C4
+mega.pid.6=0xEA60
 mega.upload_port.0.vid=0x2341
 mega.upload_port.0.pid=0x0010
 mega.upload_port.1.vid=0x2341
@@ -245,7 +247,9 @@ mega.upload_port.4.vid=0x2341
 mega.upload_port.4.pid=0x0210
 mega.upload_port.5.vid=0x2341
 mega.upload_port.5.pid=0x0242
-mega.upload_port.6.board=mega
+mega.upload_port.6.vid=0x10C4
+mega.upload_port.6.pid=0xEA60
+mega.upload_port.7.board=mega
 
 mega.upload.tool=avrdude
 mega.upload.tool.default=avrdude