palmetto: Enable mboxd

When we move to the 4.13 kernel tree, the LPC bus needs to be configured
through the ASPEED_LPC_CTRL_IOCTL_MAP ioctl or else the BMC will not
expose the boot firmware to the host.

We enable it on Palmetto despite P8 host firmware not speaking the mbox
protocol, as mboxd in that case sits there and doesn't do much aside
from configure the LPC firmware mapping to point to flash. In the future
if someone adds support to the host firmware, the BMC will not require
any changes.

Tested: Booted on Palmetto host up to Petitboot
Change-Id: Ic6fa9b927b7bac400661ea73da9eb67ddb51028a
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/meta-openbmc-machines/meta-openpower/meta-ibm/meta-palmetto/recipes-phosphor/images/obmc-phosphor-image.bbappend b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-palmetto/recipes-phosphor/images/obmc-phosphor-image.bbappend
new file mode 100644
index 0000000..aa57bbf
--- /dev/null
+++ b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-palmetto/recipes-phosphor/images/obmc-phosphor-image.bbappend
@@ -0,0 +1 @@
+OBMC_IMAGE_EXTRA_INSTALL_append = " mboxd"