Update GPU inventory as a FRU property

Added:
    - YAML for FRU field.
    - Updated inventory.py data file.
    - Updated new field in the test documentation.

Resolves  openbmc/openbmc-test-automation#1307

Change-Id: I55d308cf9269e5f8ff14b577b6a058a813d43831
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/tests/test_inventory.robot b/tests/test_inventory.robot
index 1ba6152..4692088 100644
--- a/tests/test_inventory.robot
+++ b/tests/test_inventory.robot
@@ -224,12 +224,14 @@
     # Example:
     # A GPU property should have the following entries:
     # "gpu":[
+    #    "FieldReplaceable",
     #    "PrettyName",
     #    "Present",
     #    "Functional"
     # ]
     # GPU inventory:
     # "/xyz/openbmc_project/inventory/system/chassis/motherboard/gv100card2": {
+    #    "FieldReplaceable": 1,
     #    "Functional": 1,
     #    "Present": 1,
     #    "PrettyName": ""