drm: dma_bufs: Fixed checkpatch issues

Fix a couple of checkpatch issues

Signed-off-by: Paul McQuade <paulmcquad@gmail.com>
[seanpaul squashed series of 4 into one patch, and changed commit msg]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180319005225.1545-1-paulmcquad@gmail.com