Extended ring buffer to allow storing raw bytes in it. API has been
extended keeping 'data item' mode untouched.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Deprecate API prefixed with sys_ring_buf_ and rename it
to ring_buf_item_ since this API is not a typical ring buffer
but ring buffer of data items (metadata + 32bit words).
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>