pldm: Add bios configuration in single json file

Currently bios attributes are added in three json configuration
files based on the attribute type(integer, string, enum).
Combining all the attributes in single bios attribute json file
to organize the attributes based on the usage pattern.

Tested:
BMC powered on successfully
Unit tests passed

Change-Id: I42cc7c2394918e48d27dca2041f8ce00509c565a
Signed-off-by: Archana Kakani <archana.kakani@ibm.com>