Add Printer Device Class source files to the Atmel Studio integration XML.

LUFA/StudioIntegration/lufa_drivers_usb_class.xml

@@ -114,6 +114,8 @@
 
 			<build type="header-file" value="Drivers/USB/Class/PrinterClass.h"/>
 			<build type="header-file" value="Drivers/USB/Class/Common/PrinterClassCommon.h"/>
+			<build type="header-file" value="Drivers/USB/Class/Device/PrinterClassDevice.h"/>
+			<build type="c-source"    value="Drivers/USB/Class/Device/PrinterClassDevice.c"/>
 			<build type="header-file" value="Drivers/USB/Class/Host/PrinterClassHost.h"/>
 			<build type="c-source"    value="Drivers/USB/Class/Host/PrinterClassHost.c"/>
 		</module>
@@ -167,4 +169,4 @@
 			<require idref="lufa.drivers.usb.class.si"/>
 		</module>
 	</asf>
-</lufa>
+</lufa>