drm/i915: convert to new logging macros in i915/intel_gvt.c

This converts the use of printk based logging macros in i915/intel_gvt.c
with the new struct drm_device based logging macros.

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/44f3839820a32ed03d73dc56a6ef3581994802c9.1578560355.git.wambui.karugax@gmail.com