exiftag: reflow the code

Move the warning on unsupported units to the swicth-case. Move fetching the
pending tags down to where we use them.

gst-libs/gst/tag/gstexiftag.c

@@ -2565,14 +2565,6 @@ deserialize_resolution (GstExifReader * exif_reader,
     unit = GST_READ_UINT16_BE (tagdata->offset_as_data);
   }
 
-  if (unit != 2 && unit != 3) {
-    GST_WARNING ("Invalid resolution unit, ignoring PPI tags");
-    return 0;
-  }
-
-  xres = gst_exif_reader_get_pending_tag (exif_reader, EXIF_TAG_XRESOLUTION);
-  yres = gst_exif_reader_get_pending_tag (exif_reader, EXIF_TAG_YRESOLUTION);
-
   switch (unit) {
     case 2:                    /* inch */
       multiplier = 1;
@@ -2581,15 +2573,16 @@ deserialize_resolution (GstExifReader * exif_reader,
       multiplier = 1 / 2.54;
       break;
     default:
-      multiplier = 1;
-      g_assert_not_reached ();
-      break;
+      GST_WARNING ("Invalid resolution unit, ignoring PPI tags");
+      return 0;
   }
 
+  xres = gst_exif_reader_get_pending_tag (exif_reader, EXIF_TAG_XRESOLUTION);
   if (xres) {
     parse_exif_rational_tag (exif_reader, GST_TAG_IMAGE_HORIZONTAL_PPI,
         xres->count, xres->offset, multiplier, FALSE);
   }
+  yres = gst_exif_reader_get_pending_tag (exif_reader, EXIF_TAG_YRESOLUTION);
   if (yres) {
     parse_exif_rational_tag (exif_reader, GST_TAG_IMAGE_VERTICAL_PPI,
         yres->count, yres->offset, multiplier, FALSE);