The function get_pt_type is defined in the gtt.c file, but not
called elsewhere, so delete this unused function.

drivers/gpu/drm/i915/gvt/gtt.c:285:19: warning: unused function 'get_pt_type'.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2277Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220926064044.53016-1-jiapeng.chong@linux.alibaba.comReviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>