configs/ts7680: bump Linux to 4.9, to fix build with gcc >= 8.x

The TS-7680 defconfig does not build with gcc 8.x and 9.x because it
uses an old 3.14 kernel. Technologic Systems, the board manufacturer
recently released an updated 4.9 based kernel on a separate repository
on github.

Bump the kernel release from 3.14.28 to 4.19.186 and update the linux
defconfig name as requested in the TS-7680 documentation [1].

[1] https://wiki.embeddedarm.com/wiki/TS-7680#Linux_4.9.y

Signed-off-by: Julien Grossholtz <julien.grossholtz@openest.io>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/technologic/ts7680/readme.txt

@@ -10,8 +10,7 @@ Wi-Fi, microSD card, eMMC, NOR Flash, USB host port, CAN ports,
 relays and ADC/DAC. More details on the board here:
 https://wiki.embeddedarm.com/wiki/TS-7680
 
-The TS-7680 uses a 3.14.28 Linux kernel provided by
-Technologic Systems.
+The TS-7680 uses a 4.9 Linux kernel provided by Technologic Systems.
 
 To build the default configuration you only have to run:
 

configs/ts7680_defconfig

@@ -1,11 +1,11 @@
 BR2_arm=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_14=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_9=y
 BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/technologic/ts7680/genimage.cfg"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
-BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="$(call github,embeddedarm,linux-3.14.28-imx28,ff01621df09b97d9fd546d1b49f4013060142892)/linux-ff01621df09b97d9fd546d1b49f4013060142892.tar.gz"
-BR2_LINUX_KERNEL_DEFCONFIG="ts76xx"
+BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="$(call github,embeddedarm,linux-4.9.y,d03d426e6abd95a973bc669315206295713c17e8)/linux-d03d426e6abd95a973bc669315206295713c17e8.tar.gz"
+BR2_LINUX_KERNEL_DEFCONFIG="ts_imx28"
 BR2_LINUX_KERNEL_UIMAGE=y
 BR2_LINUX_KERNEL_UIMAGE_LOADADDR="0x40008000"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y