RPC: Merge RPC PSA Client APIs

Originally, connection-based APIs are optional, depends on whether the
TF-M provides any.
So the RPC APIs are also separated so that they can be selected.

Later, the APIs are always provided with returning NOT SUPPORTED in case
of no connection-based APIs.
And the RPC test framework followed up by always building all the APIs.

This patch makes it further by merging all the APIs.

Change-Id: I923c24e5e83cae4e3d8f4774d776dbe8d07610c2
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
15 files changed