media: cec: extron-da-hd-4k-plus: don't use -1 as an error code

The logic at get_edid_tag_location() returns either an offset
or an error condition. However, the error condition uses a
non-standard "-1" value. This hits a Coverity bug, as Coverity
assumes that positive values are underflow. While this is a
false positive, returning error codes as -1 is an issue.

So, instead, use -ENOENT to indicate that the tag was not found.

Fixes: 056f2821b6 ("media: cec: extron-da-hd-4k-plus: add the Extron DA HD 4K Plus CEC driver")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c

@@ -348,12 +348,12 @@ static int get_edid_tag_location(const u8 *edid, unsigned int size,
 
 	/* Return if not a CTA-861 extension block */
 	if (size < 256 || edid[0] != 0x02 || edid[1] != 0x03)
-		return -1;
+		return -ENOENT;
 
 	/* search tag */
 	d = edid[0x02] & 0x7f;
 	if (d <= 4)
-		return -1;
+		return -ENOENT;
 
 	i = 0x04;
 	end = 0x00 + d;
@@ -371,7 +371,7 @@ static int get_edid_tag_location(const u8 *edid, unsigned int size,
 			return offset + i;
 		i += len + 1;
 	} while (i < end);
-	return -1;
+	return -ENOENT;
 }
 
 static void extron_edid_crc(u8 *edid)