board/freescale: add support for Image.gz to post-image

For the i.MX8 often an Image.gz is built. With these changes, if
BR2_LINUX_KERNEL_IMAGEGZ=y, the correct Image.gz file is now put into
the generated image instead of falling back to the non-existent zImage.

Signed-off-by: Hanspeter Portner <dev@open-music-kontrollers.ch>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

board/freescale/common/imx/post-image.sh

@@ -25,6 +25,8 @@ linux_image()
 		echo "\"uImage\""
 	elif grep -Eq "^BR2_LINUX_KERNEL_IMAGE=y$" ${BR2_CONFIG}; then
 		echo "\"Image\""
+	elif grep -Eq "^BR2_LINUX_KERNEL_IMAGEGZ=y$" ${BR2_CONFIG}; then
+		echo "\"Image.gz\""
 	else
 		echo "\"zImage\""
 	fi