[BUGFIX] need to parse field value for maxitems = 1 with MM table

If a select field has an MM table like sys_category_record_mm
it is necessary to parse the field value even if maxitems = 1
Furthermore, this really fixes #69836 as that was actually
only a workaround.

Resolves: #70081
Relates: #69836
Releases: master

Change-Id: I13c286048d666fa196d5dc83a72a3612090c4e25
Reviewed-on: http://review.typo3.org/43531


Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>