drm/i915/hdcp: Add update_pipe early return

Currently intel_hdcp_update_pipe() is also getting called for non-hdcp
connectors and get through its conditional code flow, which is completely
unnecessary for non-hdcp connectors, therefore it make sense to
have an early return. No functional change.

v2:
- rebased.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200805114521.867-2-anshuman.gupta@intel.com