witherspoon: Enable hwmon-iio bridge

Add the hwmon-iio bridge to the witherspoon config fragment.

Change-Id: I4d0bc9717015258dfee5a8fe90b26d6b26aaa7fc
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-ibm/meta-witherspoon/recipes-kernel/linux/linux-obmc/witherspoon.cfg b/meta-ibm/meta-witherspoon/recipes-kernel/linux/linux-obmc/witherspoon.cfg
index 6d74746..029e843 100644
--- a/meta-ibm/meta-witherspoon/recipes-kernel/linux/linux-obmc/witherspoon.cfg
+++ b/meta-ibm/meta-witherspoon/recipes-kernel/linux/linux-obmc/witherspoon.cfg
@@ -1,4 +1,5 @@
 CONFIG_HWMON=y
+CONFIG_SENSORS_IIO_HWMON=y
 CONFIG_SENSORS_TMP421=y
 CONFIG_SENSORS_MAX31785=y
 CONFIG_SENSORS_UCD9000=y