x11/cde*: Remove unused iconv dependencies

CDE only uses iconv.h. It does not need libiconv nor does it need binconv.
Remove the redundant dependencies.

Reported by: arrowd
Initial patcy by: arrowd
PR: 290743
MFH: 2025Q4

(cherry picked from commit 5df36de6d36bd102a7c71fc7d2ec8d789c87ef6b)