Untangle BindingCodecContext/BindingNormalizedNodeCodecRegistry

Untangle BindingCodecContext/BindingNormalizedNodeCodecRegistry

The relationship here should be clear -- a BindingCodecContext is
self-contained and should not be subject to dynamism. The registry
maintains a 'current' codec.

Achieving this is very simple -- just do not perform upcalls to
Registry when we are looking for a streamer, it would just loop
back to BindingCodecContext and we want to be consistent, i.e. do
not try to upcall to a different BindingCodecContext.

JIRA: MDSAL-392
Change-Id: I720738f122ba89974e32c91ed8c7f3a059c21690
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>