MB-8602: Rename _all_docs specific function

There was one capi_view:view_merge_params() case which was specific
to _all_docs. That one got renamed.

Change-Id: I268117d848013480427329f4016ed1e7d4f9e020
Reviewed-on: http://review.couchbase.org/27421
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>