drm/hibmc: Remove references to struct drm_device.pdev

Using struct drm_device.pdev is deprecated. Convert hibmc to struct
drm_device.dev. No functional changes.

v3:
	* rebased

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tian Tao <tiantao6@hisilicon.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Xinliang Liu <xinliang.liu@linaro.org>
Cc: Tian Tao  <tiantao6@hisilicon.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Cc: Chen Feng <puck.chen@hisilicon.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210107080748.4768-4-tzimmermann@suse.de