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/templates/default/bblayers.conf.sample b/meta-ampere/meta-mitchell/conf/templates/default/bblayers.conf.sample
new file mode 100644
index 0000000..a6e860f
--- /dev/null
+++ b/meta-ampere/meta-mitchell/conf/templates/default/bblayers.conf.sample
@@ -0,0 +1,31 @@
+# LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
+# changes incompatibly
+LCONF_VERSION = "8"
+
+BBPATH = "${TOPDIR}"
+BBFILES ?= ""
+
+BBLAYERS ?= " \
+  ##OEROOT##/meta \
+  ##OEROOT##/meta-openembedded/meta-oe \
+  ##OEROOT##/meta-openembedded/meta-networking \
+  ##OEROOT##/meta-openembedded/meta-perl \
+  ##OEROOT##/meta-openembedded/meta-python \
+  ##OEROOT##/meta-security \
+  ##OEROOT##/meta-phosphor \
+  ##OEROOT##/meta-aspeed \
+  ##OEROOT##/meta-ampere \
+  ##OEROOT##/meta-ampere/meta-mitchell \
+  "
+BBLAYERS_NON_REMOVABLE ?= " \
+  ##OEROOT##/meta \
+  ##OEROOT##/meta-openembedded/meta-oe \
+  ##OEROOT##/meta-openembedded/meta-networking \
+  ##OEROOT##/meta-openembedded/meta-perl \
+  ##OEROOT##/meta-openembedded/meta-python \
+  ##OEROOT##/meta-security \
+  ##OEROOT##/meta-phosphor \
+  ##OEROOT##/meta-aspeed \
+  ##OEROOT##/meta-ampere \
+  ##OEROOT##/meta-ampere/meta-mitchell \
+  "