Header has used the references to struct device without it definition
or declaration. Hence resulting in compilation warning such as

  "'struct device' declared inside parameter list..."

This changes adds a declaration to struct device in the header to avoid
any such warnings.
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
cc: Takashi Iwai <tiwai@suse.de>
cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1550293499-5560-1-git-send-email-ramalingam.c@intel.com