Add CONFIG_IGB=m

The igb module is used by AOC-SG-I2 NIC which is supported on boston systems.

Signed-off-by: Mauro S. M. Rodrigues <maurosr@linux.vnet.ibm.com>
diff --git a/openpower/configs/linux/skiroot_p9_defconfig b/openpower/configs/linux/skiroot_p9_defconfig
index 309f182..e52fd9f 100644
--- a/openpower/configs/linux/skiroot_p9_defconfig
+++ b/openpower/configs/linux/skiroot_p9_defconfig
@@ -133,6 +133,7 @@
 CONFIG_E100=m
 CONFIG_E1000=m
 CONFIG_E1000E=m
+CONFIG_IGB=m
 CONFIG_IXGB=m
 CONFIG_IXGBE=m
 CONFIG_I40E=m