obmc-flash-bmc: Add u-boot update

Add function to update the u-boot mtd by doing a direct flash write.
Add it to the read-only function since u-boot is considered a
non-writable partition.

Change-Id: I73e76ba7153f18b03418ac9b181abc5d31f61f17
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/common/recipes-phosphor/flash/phosphor-software-manager/obmc-flash-bmc-ubiro@.service b/common/recipes-phosphor/flash/phosphor-software-manager/obmc-flash-bmc-ubiro@.service
index 3e4c15d..7c2a252 100644
--- a/common/recipes-phosphor/flash/phosphor-software-manager/obmc-flash-bmc-ubiro@.service
+++ b/common/recipes-phosphor/flash/phosphor-software-manager/obmc-flash-bmc-ubiro@.service
@@ -1,9 +1,10 @@
 [Unit]
-Description=Create read-only ubi volumes %I
+Description=Store read-only images %I to BMC storage
 
 [Service]
 Type=oneshot
 RemainAfterExit=no
 ExecStart=/usr/bin/env obmc-flash-bmc ubiro {RO_MTD} rofs-%i %i
 ExecStart=/usr/bin/env obmc-flash-bmc ubikernel {KERNEL_MTD} kernel-%i %i
+ExecStart=/usr/bin/env obmc-flash-bmc mtduboot u-boot %i
 SyslogIdentifier=obmc-flash-bmc