pldmd: Migrate to pldm_pdr_add_check()

pldm_pdr_add() is deprecated in libpldm as it uses assert() to
communicate to the caller that an error occurred. pldm_pdr_add_check()
instead returns a value that indicates success or failure.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Icca92fd742f07fb935202a9d9e62f5648916b12b