meta-ibm: p10bmc: set windows-num override

p10bmc machines utilize the reserved 64MB of memory for both HIOMAP and
MCTP transport implementations. HIOMAP gets the first 63MB and MCTP gets
the last 1MB.

Tested:
- Confirmed mboxd started with "--window-num 63" parameter

Change-Id: I2f82875da4b75dbcc4fdd59e9dcea8f0fc46154a
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-ibm/recipes-phosphor/mboxd/mboxd_%.bbappend b/meta-ibm/recipes-phosphor/mboxd/mboxd_%.bbappend
index 0e35037..51c00e4 100644
--- a/meta-ibm/recipes-phosphor/mboxd/mboxd_%.bbappend
+++ b/meta-ibm/recipes-phosphor/mboxd/mboxd_%.bbappend
@@ -1,5 +1,6 @@
 MBOXD_FLASH_SIZE:ibm-ac-server = "64M"
 MBOXD_FLASH_SIZE:p10bmc = "64M"
+MBOXD_WINDOW_NUM:p10bmc = "63"
 
 FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"