meta-ibm: p10bmc: add a MCTP DISTRO_FEATURES switch

The switch enables AF_MCTP and adds the `mctp` tool and `mctpd` so we
can setup and manage an in-kernel MCTP network.

Enable it for p10bmc and also add CONFIG_TUN so we can use a tun device
to transport packets between the kernel and the astlpc interface
implemented in libmctp.

Change-Id: I21d0af9e751f91975c760b4b4708b3b401b95417
Signed-off-by: Rashmica Gupta <rashmica@linux.ibm.com>
diff --git a/meta-ibm/recipes-kernel/linux/linux-aspeed/p10bmc.cfg b/meta-ibm/recipes-kernel/linux/linux-aspeed/p10bmc.cfg
index 74cee4d..94bb5a3 100644
--- a/meta-ibm/recipes-kernel/linux/linux-aspeed/p10bmc.cfg
+++ b/meta-ibm/recipes-kernel/linux/linux-aspeed/p10bmc.cfg
@@ -16,3 +16,4 @@
 CONFIG_USB_SERIAL=y
 CONFIG_USB_SERIAL_PL2303=y
 CONFIG_IPMI_KCS_BMC_CDEV_RAW=y
+CONFIG_TUN=y