drm/bridge: fix typo in Kconfig

fix 's/controller/controllers/'

in the sentence:
Most display controller handle display connectors...

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210326103216.7918-2-dafna.hirschfeld@collabora.com