[u-boot-mgr]: Initial u-boot mgr hardening intf

Initial u-boot mgr to harden interface and usage. This
exposes method in D-Bus which other daemon can use to update
U-Boot environment variables, instead of directly using
fw_printenv  or fw_setenv tools.

Tested:
Verified able to query the ReadAll, Read and Write
method exposed in this interface.

Signed-off-by: Richard Marian Thomaiyar <richard.marian.thomaiyar@linux.intel.com>
Change-Id: I21772c8f30b7c68f5c9a2da3d44217ea2f533014
diff --git a/xyz.openbmc_project.U_Boot.Environment.Manager.service b/xyz.openbmc_project.U_Boot.Environment.Manager.service
new file mode 100644
index 0000000..faae3bf
--- /dev/null
+++ b/xyz.openbmc_project.U_Boot.Environment.Manager.service
@@ -0,0 +1,13 @@
+[Unit]
+Description=Phosphor U-Boot environment manager
+
+[Service]
+Restart=always
+RestartSec=2
+ExecStart=/usr/bin/phosphor-u-boot-env-mgr
+StartLimitInterval=0
+Type=dbus
+BusName=xyz.openbmc_project.U_Boot.Environment.Manager
+
+[Install]
+WantedBy=basic.target