can: length: can_fd_len2dlc(): simplify length calculcation

If the length paramter in len2dlc() exceeds the size of the len2dlc array, we
return 0xF. This is equal to the last 16 members of the array.

This patch removes these members from the array, uses ARRAY_SIZE() for the
length check, and returns CANFD_MAX_DLC (which is 0xf).

Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-9-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/dev/length.c

@@ -27,15 +27,13 @@ static const u8 len2dlc[] = {
 	13, 13, 13, 13, 13, 13, 13, 13,	/* 25 - 32 */
 	14, 14, 14, 14, 14, 14, 14, 14,	/* 33 - 40 */
 	14, 14, 14, 14, 14, 14, 14, 14,	/* 41 - 48 */
-	15, 15, 15, 15, 15, 15, 15, 15,	/* 49 - 56 */
-	15, 15, 15, 15, 15, 15, 15, 15	/* 57 - 64 */
 };
 
 /* map the sanitized data length to an appropriate data length code */
 u8 can_fd_len2dlc(u8 len)
 {
-	if (unlikely(len > 64))
-		return 0xF;
+	if (len >= ARRAY_SIZE(len2dlc))
+		return CANFD_MAX_DLC;
 
 	return len2dlc[len];
 }