pldm: Rearranging datatype declaration

This commit adds support to eliminating duplication of datatypes which
enhancing clarity and manageability throughout the pldm repository.
This is rearrangement of declaration of data types so it can be used
host-bmc and oem layer both the places.

Change-Id: Ieb1232884b8e2128e8bf97dafd01e4ad5524ede0
Signed-off-by: Kamalkumar Patel <kamalkumar.patel@ibm.com>