drm/i915/gen9+: Add has_ipc flag in device info structure

New Isochronous Priority Control (IPC) capability is introduced in newer
GEN platforms. This patch adds a device info flag to indicate if platform
supports IPC. Patch also sets this flag in supported platforms.

Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170817134529.2839-7-mahesh1.kumar@intel.com