configs/imx7d-sdb: add extlinux.conf support

imx7d-sdb has been converted to use disto boot in U-Boot.

Add extlinux.conf support so that the board can boot correctly.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Pierre-Jean Texier <texier.pj2@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/freescale/imx7dsdb/rootfs_overlay/boot/extlinux/extlinux.conf

@@ -0,0 +1,4 @@
+Label imx7d-sabresd-buildroot
+  kernel /boot/zImage
+  devicetree /boot/imx7d-sdb.dtb
+  append root=PARTUUID=${uuid} rootwait rw console=${console},${baudrate}

configs/imx7d-sdb_defconfig

@@ -17,6 +17,7 @@ BR2_LINUX_KERNEL_DEFCONFIG="imx_v6_v7"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="imx7d-sdb"
 BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+BR2_LINUX_KERNEL_INSTALL_TARGET=y
 
 # U-Boot
 BR2_TARGET_UBOOT=y
@@ -26,6 +27,7 @@ BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2020.01"
 BR2_TARGET_UBOOT_FORMAT_DTB_IMX=y
 
 # Filesystem
+BR2_ROOTFS_OVERLAY="board/freescale/imx7dsdb/rootfs_overlay"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/freescale/common/imx/post-image.sh"
 BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y