[Processing] Fix GRASS7 v.db.select (fixes Redmine #11212)

python/plugins/processing/algs/grass7/description/v.db.select.txt

@@ -3,12 +3,12 @@ Prints vector map attributes
 Vector (v.*)
 ParameterVector|map|Input vector map |-1|False
 ParameterNumber|layer|Layer Number|1|None|1
-ParameterString|columns|Name of attribute column(s), comma separated|
+ParameterString|columns|Name of attribute column(s), comma separated|None|False|True
 ParameterBoolean|-c|Do not include column names in output|False
-ParameterString|separator|Output field separator|,
-*ParameterString|where|WHERE conditions of SQL statement without 'where' keyword|
-*ParameterString|vertical_separator|Output vertical record separator|
-*ParameterString|null_value|Null value indicator|
+ParameterString|separator|Output field separator|,|False|True
+*ParameterString|where|WHERE conditions of SQL statement without 'where' keyword|None|False|True
+*ParameterString|vertical_separator|Output vertical record separator|None|False|True
+*ParameterString|null_value|Null value indicator|None|False|True
 *ParameterBoolean|-v|Vertical output (instead of horizontal)|False
 *ParameterBoolean|-r|Print minimal region extent of selected vector features instead of attributes|False
 OutputFile|file|Attributes