configs/asus_tinker-s_rk3288: new defconfig

This commit duplicates the asus_tinker_rk3288_defconfig changing:

  - BR2_LINUX_KERNEL_INTREE_DTS_NAME to rk3288-tinker-s
  - BR2_TARGET_UBOOT_BOARD_DEFCONFIG to tinker-s-rk3288
  - extlinux.conf devicetree to /boot/rk3288-tinker-s.dtb
  - root device format to <major>:<minor> in order to prevent the kernel to mount rootfs
    from the wrong device
  - Add Flávio Tapajós for configs/asus_tinker-s_rk3288_defconfig and for
    configs/asus_tinker-s_rk3288_defconfig and for board/asus/tinker-s

Signed-off-by: Flávio Tapajós <flavio.tapajos@newtesc.com.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/asus/tinker-s/extlinux.conf

@@ -0,0 +1,4 @@
+label Tinker linux
+  kernel /boot/uImage
+  devicetree /boot/rk3288-tinker-s.dtb
+  append console=ttyS2,115200n8 root=179:1 rootwait

board/asus/tinker-s/post-build.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+MKIMAGE=$HOST_DIR/bin/mkimage
+BOARD_DIR="$(dirname $0)"
+
+$MKIMAGE -n rk3288 -T rksd -d $BINARIES_DIR/u-boot-tpl.bin $BINARIES_DIR/u-boot-tpl.img
+cat $BINARIES_DIR/u-boot-tpl.img $BINARIES_DIR/u-boot-spl-dtb.bin > $BINARIES_DIR/u-boot-tpl-spl-dtb.img
+
+install -m 0644 -D $BOARD_DIR/extlinux.conf $TARGET_DIR/boot/extlinux/extlinux.conf

board/asus/tinker-s/readme.txt

@@ -0,0 +1,43 @@
+Tinker S RK3288
+=============
+
+Tinker Board is a Single Board Computer (SBC) in an ultra-small form
+factor that offers class-leading performance while leveraging outstanding
+mechanical compatibility. The "S" variant of the Tinker Board has eMMC
+
+Tinker link:
+https://www.asus.com/br/motherboards-components/single-board-computer/all-series/tinker-board-s/
+
+Wiki link:
+https://openedev.amarulasolutions.com/display/ODWIKI/Tinker+RK3288
+
+How to build it
+===============
+
+  $ make asus_tinker-s_rk3288_defconfig
+
+Then you can edit the build options using
+
+  $ make menuconfig
+
+Compile all and build rootfs image:
+
+  $ make
+
+Prepare your SDCard
+===================
+
+Buildroot generates a ready-to-use SD card image that you can flash directly to
+the card. The image will be in output/images/sdcard.img.
+You can write this image directly to an SD card device (i.e. /dev/xxx):
+
+  $ sudo dd if=output/images/sdcard.img of=/dev/xxx
+  $ sudo sync
+
+Finally, you can insert the SD card to the Tinker RK3288 board and boot it.
+
+NOTE:
+USB power supply requires more than the standard 500mA USB current, so
+this board must be supplied from a capable port or from an external
+AC/DC adapter. Otherwise it will hang forever while loading the kernel
+image.