Fix handling of getting and setting v4l2 controls.
The unpatched implementation depends on a Linux specific behaviour of getsubopt(3):

If the first suboption in optionp is recognized, getsubopt() returns
the index of the matching suboption element in tokens. Otherwise, -1
is returned and *valuep is the entire name[=value] string.

The "Otherwise..." part is implemented differently on FreeBSD. The file gets now
patched to use a local and reduced implementation of getsubopt(3) to fix this

Approved by: nox