linux-headers: bump 4.{14, 15, 16}.x series

[Peter: drop 4.16.x change]
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit ea4921d875a45fe03b86b672a432ff2e88268733)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/linux-headers/Config.in.host

@@ -248,6 +248,6 @@ config BR2_DEFAULT_KERNEL_HEADERS
 	default "4.11.12"	if BR2_KERNEL_HEADERS_4_11
 	default "4.12.14"	if BR2_KERNEL_HEADERS_4_12
 	default "4.13.16"	if BR2_KERNEL_HEADERS_4_13
-	default "4.14.33"	if BR2_KERNEL_HEADERS_4_14
-	default "4.15.17"	if BR2_KERNEL_HEADERS_4_15
+	default "4.14.35"	if BR2_KERNEL_HEADERS_4_14
+	default "4.15.18"	if BR2_KERNEL_HEADERS_4_15
 	default BR2_DEFAULT_KERNEL_VERSION if BR2_KERNEL_HEADERS_VERSION