vfs5011: do duplicate line search for 30 lines

It seems that on faster devices, the driver can get more duplicate lines.
Without this change scan looks too stretched.

Suggested by: Thomas Rinsma <thomasrinsma@gmail.com>

libfprint/drivers/vfs5011.c

@@ -353,7 +353,7 @@ int vfs5011_rescale_image(unsigned char *image, int input_lines,
 	enum {
 		RESOLUTION = 10,
 		MEDIAN_FILTER_SIZE = 13,
-		MAX_OFFSET = 10,
+		MAX_OFFSET = 30,
 		GOOD_OFFSETS_CRITERION = 20,
 		GOOD_OFFSETS_THRESHOLD = 3
 	};