drm/i915/atomic: use struct drm_device logging macros

Convert to the new struct drm_based logging macros to replace the printk
based macros in i915/display/intel_atomic_plane.c.

Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200121134559.17355-2-wambui.karugax@gmail.com