drm: plug memory leak on drm_setup() failure

Currently we fail to free and detach the drm_file when drm_setup() fails.
Use the drm_close_helper to do address that.

Change-Id: Iec5d8e21af33b50e61255a73a488dfe739a26934
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114084410.15266-2-emil.l.velikov@gmail.com
Git-commit: 4acc5be3cd89cc4132d8456144ee066905a58e41
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Nilaan Gunabalachandran <ngunabal@codeaurora.org>