board: sl28: move to OF_UPSTREAM

Use the new device devicetree files in dts/upstream/ and delete the old
ones. Still keep the -u-boot.dtsi with all u-boot specifics around.

There is one catch and that is fsl-ls1028a-kontron-sl28-var3.dts which
is not available upstream (yet!). For now, the base dts is used for this
variant as this only differ in the compatible and the (human readable)
model name.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/kontron_sl28_defconfig b/configs/kontron_sl28_defconfig
index 639c5c6..adc1d50 100644
--- a/configs/kontron_sl28_defconfig
+++ b/configs/kontron_sl28_defconfig
@@ -11,7 +11,7 @@
 CONFIG_ENV_SIZE=0x2000
 CONFIG_ENV_OFFSET=0x3e0000
 CONFIG_ENV_SECT_SIZE=0x10000
-CONFIG_DEFAULT_DEVICE_TREE="fsl-ls1028a-kontron-sl28"
+CONFIG_DEFAULT_DEVICE_TREE="freescale/fsl-ls1028a-kontron-sl28"
 CONFIG_SPL_TEXT_BASE=0x18010000
 CONFIG_SYS_FSL_SDHC_CLK_DIV=1
 CONFIG_OF_LIBFDT_OVERLAY=y
@@ -73,7 +73,8 @@
 CONFIG_CMD_RNG=y
 CONFIG_OF_CONTROL=y
 CONFIG_SPL_OF_CONTROL=y
-CONFIG_OF_LIST="fsl-ls1028a-kontron-sl28 fsl-ls1028a-kontron-sl28-var1 fsl-ls1028a-kontron-sl28-var2 fsl-ls1028a-kontron-sl28-var3 fsl-ls1028a-kontron-sl28-var4"
+CONFIG_OF_UPSTREAM=y
+CONFIG_OF_LIST="freescale/fsl-ls1028a-kontron-sl28 freescale/fsl-ls1028a-kontron-sl28-var1 freescale/fsl-ls1028a-kontron-sl28-var2 freescale/fsl-ls1028a-kontron-sl28-var4"
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y