chinese/fcitx: Remove nop options helper

Options helpers are ineffective when set after bsd.port.options.mk.
DOCS_EXTRA_PATCHES_OFF is not needed. A build without DOCS is
already working via %%PORTDOCS%% in the plist even without
files/nodocs-doc_CMakeLists.txt (which also no longer applies).

Reported by: tobik (in D19553)