meta-phosphor: Add Mailbox Daemon

Change-Id: Ie65c83cfde93ae47c0dd1f9ffcfc37ce9566f18e
Tested: Built image and mboxd then ran on lanyang
	motherboard, checked the mailbox daemon on BMC,
	used instruction "ps -l" to check mailbox process
	status, the result like
	"mboxd --flash 64M --window-size 1M"
Signed-off-by: Brian Yang <yang.brianc.w@inventec.com>
diff --git a/meta-lanyang/recipes-phosphor/mboxd/mboxd.bbappend b/meta-lanyang/recipes-phosphor/mboxd/mboxd.bbappend
new file mode 100644
index 0000000..8b6248a
--- /dev/null
+++ b/meta-lanyang/recipes-phosphor/mboxd/mboxd.bbappend
@@ -0,0 +1 @@
+MBOXD_FLASH_SIZE = "64M"