README: remove section about pldm daemon

The section describing the pldm daemon was added a bit prematurely. This
is still work in progress alongwith the MCTP design. This will be
described later on once the design is finalised.

Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
Change-Id: I0a13c8e561acce64b74ec5f69e6dcab881d087b7