xerox_mfp: add Xerox WorkCentre 3335

Works OK, but, when scanning in automatic feeder mode, only the first page is scanned:
e.g. if run
SANE_DEBUG_XEROX_MFP=4 skanlite
skanlite thinks that scanning has been finished after the first page, but the scanner continues to work and debug messages about reading data from the scanner (sane_xerox_mfp_read: <..>) continue to be printed.

Signed-off-by: Mikhail Novosyolov <m.novosyolov@rosalinux.ru>

backend/xerox_mfp.conf.in

@@ -251,6 +251,9 @@ usb 0x0924 0x42da
 #Xerox WorkCentre 3225
 usb 0x0924 0x42dc
 
+#Xerox WorkCentre 3335
+usb 0x0924 0x42e2
+
 ###################
 ### Dell Models ###
 ###################

doc/descriptions/xerox_mfp.desc

@@ -43,6 +43,12 @@
 :usbid "0x0924" "0x42dc"
 :status :good
 
+:model "WorkCentre 3335"
+:interface "USB"
+:usbid "0x0924" "0x42e2"
+:status :basic
+:comment "When scanning from automatic feeder, only the first page is scanned"
+
 :mfg "Dell"
 :url "http://www.dell.com/"