xerox_mfp: Add Samsung Xpress M2070

Device is tested with latest sane (1.0.27) on several Linux
distributions (Void Linux + Ubuntu), using the proposed addition.

Frontends used to test are: simple-scan and xsane

backend/xerox_mfp.conf.in

@@ -196,6 +196,9 @@ usb 0x04e8 0x3466
 #Samsung C460 Series
 usb 0x04e8 0x3468
 
+#Samsung M2070 Series
+usb 0x04e8 0x3469
+
 #Samsung C1860FW
 usb 0x04e8 0x346b
 

doc/descriptions/xerox_mfp.desc

@@ -383,6 +383,11 @@
 :usbid "0x04e8" "0x3468"
 :status :untested
 
+:model "M2070"
+:interface "USB"
+:usbid "0x04e8" "0x3469"
+:status :good
+
 :model "C1860FW"
 :interface "USB"
 :usbid "0x04e8" "0x346b"