drm/i915/hdcp: Move HDCP enc status timeout to header

DP MST stream encryption status requires time of a link frame
in order to change its status, but as there were some HDCP
encryption timeout observed earlier, it is safer to use
ENCRYPT_STATUS_CHANGE_TIMEOUT_MS timeout for stream status too,
it requires to move the macro to a header.
It will be used by both HDCP{1.x,2.x} stream status timeout.

Related: 'commit 7e90e8d0 ("drm/i915: Increase timeout for Encrypt
status change")'
Cc: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Tested-by: Karthik B S <karthik.b.s@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210111081120.28417-7-anshuman.gupta@intel.com