drm/msm: Add memory stats to fdinfo

Use the new helper to export stats about memory usage.

v2: Drop unintended hunk
v3: Rebase

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230524155956.382440-7-robdclark@gmail.com