kgsl/drm: Add gem_info for memps.

changelog v3 : add BUG_ON postclose condition.

Changelog v2 : add open/postclose for file_private.
		when we set tgid in gem_init_object. always Xorg.
		so, I move tgid to the file_private.

Changelog v1 : add load/unload api for gem_info.

This patch adds gem_info node to /sys/kernel/debug/dri/0/gem_info for
debugging. When this patch apply in the branch. we can be check gem
memory status from this node.

Change-Id: I907a771fe90b62be0fb3d72e44ebfe68d0652a0c
Signed-off-by: Eunchul Kim <chulspro.kim@samsung.com>
Signed-off-by: Taeheon Kim <th908.kim@samsung.com>
Signed-off-by: Mathew Karimpanal <kjmathew@codeaurora.org>
(cherry picked from commit 130029432c57f8811a5202b030c5a59115fff3f7)