drm: Remove redundant statement in drm_crtc_helper_set_mode()

drm: Remove redundant statement in drm_crtc_helper_set_mode()

Commit dbbfaf5f2641a ("drm: Remove bridge support from legacy helpers")
removes the drm_bridge_mode_fixup() call in drm_crtc_helper_set_mode(),
which makes the subsequent "encoder_funcs = encoder->helper_private" be
redundant, so remove it.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20241111132149.1113736-1-chenhuacai@loongson.cn
Signed-off-by: Jani Nikula <jani.nikula@intel.com>