drm/i915/ddi: Remove redundant intel_connector NULL check

Remove redundant intel_connector NULL check. Having it here just
creates further confusion and also the variable already gets
dereferenced before the aforementioned NULL check

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231006072830.581487-1-suraj.kandpal@intel.com