kernel-headers: bump 2.6.28.x version

toolchain/kernel-headers/Config.in

@@ -62,6 +62,6 @@ config BR2_DEFAULT_KERNEL_HEADERS
 	default "2.6.25.19"	if BR2_KERNEL_HEADERS_2_6_25
 	default "2.6.26.8"	if BR2_KERNEL_HEADERS_2_6_26
 	default "2.6.27.18"	if BR2_KERNEL_HEADERS_2_6_27
-	default "2.6.28.7"	if BR2_KERNEL_HEADERS_2_6_28
+	default "2.6.28.8"	if BR2_KERNEL_HEADERS_2_6_28
 	default "2.6"		if BR2_KERNEL_HEADERS_SNAP