lavfi/smartblur: cleanup unused shorthand and doc.

doc/filters.texi

@@ -5143,7 +5143,7 @@ expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
 
 Blur the input video without impacting the outlines.
 
-A description of the accepted options follows.
+The filter accepts the following options:
 
 @table @option
 @item luma_radius, lr

libavfilter/vf_smartblur.c

@@ -289,12 +289,6 @@ static const AVFilterPad smartblur_outputs[] = {
     { NULL }
 };
 
-static const char *const shorthand[] = {
-    "luma_radius", "luma_strength", "luma_threshold",
-    "chroma_radius", "chroma_strength", "chroma_threshold",
-    NULL
-};
-
 AVFilter avfilter_vf_smartblur = {
     .name        = "smartblur",
     .description = NULL_IF_CONFIG_SMALL("Blur the input video without impacting the outlines."),