Update power supply inventory path to match MRW

I2C device access failures can lead to the correct FRU
callouts only when the inventory path of the FRU matches
in the inventory and the MRW, as a build time script
parses the MRW to map device paths to inventory items.

In the MRW it is not possible to hang a FRU off the chassis
like the BMC currently has it, so adding the motherboard
into the BMC inventory paths to match the MRW ones.

With this change, device access failures by phosphor-hwmon-readd
and witherspoon-psu-monitor will now lead to the proper
inventory object callouts.

Resolves openbmc/openbmc#2924

Change-Id: I7d76d1879ead48c95ec28c7536ae404f1fc9856d
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/meta-witherspoon/recipes-phosphor/power/witherspoon-pfault-analysis/obmc/power-supply-monitor/power-supply-monitor-1.conf b/meta-witherspoon/recipes-phosphor/power/witherspoon-pfault-analysis/obmc/power-supply-monitor/power-supply-monitor-1.conf
index b481ef2..73efd45 100644
--- a/meta-witherspoon/recipes-phosphor/power/witherspoon-pfault-analysis/obmc/power-supply-monitor/power-supply-monitor-1.conf
+++ b/meta-witherspoon/recipes-phosphor/power/witherspoon-pfault-analysis/obmc/power-supply-monitor/power-supply-monitor-1.conf
@@ -1,6 +1,6 @@
 DEVPATH=/sys/bus/i2c/devices/3-0068
 INSTANCE=1
-INVENTORY=/system/chassis/powersupply1
+INVENTORY=/system/chassis/motherboard/powersupply1
 NUM_HISTORY_RECORDS=120
 SYNC_GPIO_PATH=/dev/gpiochip0
 SYNC_GPIO_NUM=105
\ No newline at end of file