drm/i915: Removing the drrs capability enum initialization

As part of allocation of the drm_i915_private variable, drrs capability
enum is initialized to DRRS_NOT_SUPPORTED. Hence need not initialize at
each connector init.

Moreover initializing this enum at connector init will reset
the successful DRRS initialization of previous connector, as we have
the DRRS support for only one panel at a time.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>