drm/edid: rename drm_find_edid_extension() to drm_edid_find_extension()

Follow the drm_edid_ naming convention.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/b7a2c2509409de02bbd751541206586424a34725.1713259151.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>