meta-ampere: Initial AmpereOne(TM) Mt. Mitchell's non-DC-SCM BMC support

Add new Mt.Mitchell platform with basic features so that it can be
compiled and works.

Tested:
1. Compile for Mt.Mitchell successful.
2. Flash and check for the firmware can boot on the Mt.Mitchell
non-DC-SCM system without issue

Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
Change-Id: I8dc9db9029b27c0c6325c31d368cdbb614a3c8b6
diff --git a/meta-ampere/meta-mitchell/conf/machine/mtmitchell.conf b/meta-ampere/meta-mitchell/conf/machine/mtmitchell.conf
new file mode 100644
index 0000000..85e6f4f
--- /dev/null
+++ b/meta-ampere/meta-mitchell/conf/machine/mtmitchell.conf
@@ -0,0 +1,42 @@
+KMACHINE = "aspeed"
+KERNEL_DEVICETREE = "${KMACHINE}-bmc-ampere-mtmitchell.dtb"
+UBOOT_DEVICETREE = "ast2600-bletchley"
+UBOOT_MACHINE = "ast2600_openbmc_spl_defconfig"
+SPL_BINARY = "spl/u-boot-spl.bin"
+SOCSEC_SIGN_ENABLE = "0"
+
+SERIAL_CONSOLES = "115200;ttyS4"
+
+require conf/machine/include/ast2600.inc
+require conf/machine/include/obmc-bsp-common.inc
+
+FLASH_SIZE = "65536"
+VOLATILE_LOG_DIR = "no"
+
+MACHINE_FEATURES += "\
+                          obmc-bmc-state-mgmt \
+                          obmc-chassis-state-mgmt \
+                          obmc-host-ipmi \
+                          obmc-host-state-mgmt \
+                          obmc-phosphor-chassis-mgmt \
+                          obmc-phosphor-flash-mgmt \
+                         "
+
+OBMC_IMAGE_EXTRA_INSTALL:append = " \
+                                   ampere-utils \
+                                   ampere-usbnet \
+                                   phosphor-misc-usb-ctrl \
+                                   ampere-platform-init \
+                                   ampere-ipmi-oem \
+                                   phosphor-ipmi-blobs \
+                                   phosphor-ipmi-blobs-binarystore \
+                                   util-linux \
+                                  "
+
+PREFERRED_PROVIDER_virtual/obmc-chassis-mgmt = "packagegroup-obmc-ampere-apps"
+PREFERRED_PROVIDER_virtual/obmc-system-mgmt = "packagegroup-obmc-ampere-apps"
+PREFERRED_PROVIDER_virtual/obmc-flash-mgmt = "packagegroup-obmc-ampere-apps"
+PREFERRED_PROVIDER_virtual/obmc-host-ipmi-hw = "phosphor-ipmi-ssif"
+PREFERRED_PROVIDER_virtual/phosphor-led-manager-config-native = "ampere-led-manager-config-native"
+
+OVERRIDES .= ":ampere"