drm/i915/hdcp: Fix WARN_ON(data->k > INTEL_NUM_PIPES)

Initialize no. of streams transmitted on a port to zero
such that intel_hdcp_required_content_stream() can
prepared the content stream after subsequemt attmept to
enable hdcp after a HDCP failure.

v2:
- Initialize k at top level instead of else branch. [Jani]

Cc: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210119064655.1605-2-anshuman.gupta@intel.com