[simple-scan] Use fast Color Scan Mode, to resolve issue #134

[Robert Ancell <rancell src gnome org>]

commit 12e9c02a6cccf6b17aada9a26987007eb6d1360d
Author: Bartosz Kosiorek <gang65 poczta onet pl>
Date:   Tue Dec 10 20:48:14 2019 +0100

    Use fast Color Scan Mode, to resolve issue #134
    
    Also it is resolving the issue Brother MFC-J4620DW:
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=920216
    
    where is was unable to set Color mode.
    
    The allowed modes are:
    * Option 2: name='mode' title='Scan mode' type=string size=30 values=["Black & White", "Gray[Error 
Diffusion]", "True Gray", "24bit Color[Fast]"] cap=soft-select,soft-detect

 src/scanner.vala | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/scanner.vala b/src/scanner.vala
index c10992f..caf740b 100644
--- a/src/scanner.vala
+++ b/src/scanner.vala
@@ -1002,6 +1002,7 @@ public class Scanner : Object
                 {
                     Sane.VALUE_SCAN_MODE_COLOR,
                     "Color",
+                    "24bit Color[Fast]", /* brother4 driver, Brother DCP-1622WE, #134 */
                     "24bit Color", /* Seen in the proprietary brother3 driver */
                     "Color - 16 Million Colors" /* Samsung unified driver. LP: 892915 */
                 };