Move Aspeed kernel/U-Boot appends to ast2400 layer

Part 1 of 2 (meta-openbmc-bsp, meta-openbmc-machines)
diff --git a/meta-openbmc-bsp/meta-aspeed/meta-ast2400/recipes-bsp/u-boot/files/fw_env.config b/meta-openbmc-bsp/meta-aspeed/meta-ast2400/recipes-bsp/u-boot/files/fw_env.config
new file mode 100644
index 0000000..9cb3ad2
--- /dev/null
+++ b/meta-openbmc-bsp/meta-aspeed/meta-ast2400/recipes-bsp/u-boot/files/fw_env.config
@@ -0,0 +1,22 @@
+# Configuration file for fw_(printenv/setenv) utility.
+# Up to two entries are valid, in this case the redundant
+# environment sector is assumed present.
+# Notice, that the "Number of sectors" is ignored on NOR and SPI-dataflash.
+# Futhermore, if the Flash sector size is ommitted, this value is assumed to
+# be the same as the Environment size, which is valid for NOR and SPI-dataflash
+
+# NOR example
+# MTD device name	Device offset	Env. size	Flash sector size	Number of sectors
+/dev/mtd1		0x0000		0x20000		0x20000
+#/dev/mtd2		0x0000		0x4000		0x4000
+
+# MTD SPI-dataflash example
+# MTD device name	Device offset	Env. size	Flash sector size	Number of sectors
+#/dev/mtd5		0x4200		0x4200
+#/dev/mtd6		0x4200		0x4200
+
+# NAND example
+#/dev/mtd0		0x4000		0x4000		0x20000			2
+
+# Block device example
+#/dev/mmcblk0		0xc0000		0x20000