Build adm1275 driver into linux kernel by default

Barreleye requires adm1278 driver be built into kernel.
Add config to defconfig, instead of hwmon.cfg.

Signed-off-by: Yi Li <adamliyi@msn.com>
diff --git a/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig b/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
index 2b7d6e8..d2266e9 100644
--- a/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
+++ b/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
@@ -134,6 +134,9 @@
 CONFIG_DEBUG_PINCTRL=y
 CONFIG_GPIO_ASPEED=y
 CONFIG_SENSORS_POWER8_OCC_I2C=y
+CONFIG_PMBUS=y
+CONFIG_SENSORS_PMBUS=y
+CONFIG_SENSORS_ADM1275=y
 CONFIG_WATCHDOG=y
 CONFIG_ASPEED_24xx_WATCHDOG=y
 CONFIG_SSB=y