move magic number to a constant

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

app/src/main/java/com/owncloud/android/utils/theme/newm3/FilesSpecificViewThemeUtils.kt

@@ -201,13 +201,15 @@ class FilesSpecificViewThemeUtils @Inject constructor(
 
     fun primaryColorToHexString(context: Context): String {
         return withScheme(context) { scheme ->
-            String.format("#%06X", 0xFFFFFF and scheme.primary)
+            String.format("#%06X", HEX_WHITE and scheme.primary)
         }
     }
 
     companion object {
         private val TAG = FilesSpecificViewThemeUtils::class.simpleName
 
+        private const val HEX_WHITE = 0xFFFFFF
+
         private object AvatarPadding {
             @Px
             const val SMALL = 4