configs/nitrogen6*: bump kernel version

Update to latest boundary-imx_3.14.28_1.0.0_ga commit which brings the
following additions:
- Fix cache functions export when !MULTI_CACHE
https://github.com/Freescale/linux-fslc/commit/6325d57
  - Mandatory for Vivante kernel module
- Add TW686x video decoder support
- Fix OV5642 subdev/capture driver conflict
- Add GSLX680 touchscreen support

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

configs/nitrogen6sx_defconfig

@@ -31,7 +31,7 @@ BR2_TARGET_UBOOT_CUSTOM_TARBALL_LOCATION="http://github.com/boundarydevices/u-bo
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
 # Last version of branch boundary-imx_3.14.28_1.0.0_ga
-BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="https://github.com/boundarydevices/linux-imx6/tarball/d7a412b/linux-imx6-d7a412b.tar.gz"
+BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="https://github.com/boundarydevices/linux-imx6/tarball/f4c8395/linux-imx6-f4c8395.tar.gz"
 BR2_LINUX_KERNEL_DEFCONFIG="boundary"
 BR2_LINUX_KERNEL_ZIMAGE=y
 BR2_LINUX_KERNEL_INSTALL_TARGET=y

configs/nitrogen6x_defconfig

@@ -31,7 +31,7 @@ BR2_TARGET_UBOOT_CUSTOM_TARBALL_LOCATION="http://github.com/boundarydevices/u-bo
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
 # Last version of branch boundary-imx_3.14.28_1.0.0_ga
-BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="https://github.com/boundarydevices/linux-imx6/tarball/d7a412b/linux-imx6-d7a412b.tar.gz"
+BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="https://github.com/boundarydevices/linux-imx6/tarball/f4c8395/linux-imx6-f4c8395.tar.gz"
 BR2_LINUX_KERNEL_DEFCONFIG="boundary"
 BR2_LINUX_KERNEL_ZIMAGE=y
 BR2_LINUX_KERNEL_INSTALL_TARGET=y