drm/hisilicon/hibmc: Remove hibmc_ttm.c

The file is not in use. It got re-added by a rebased patch. Removing
it.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 4d4dad21 ("drm/hibmc: Remove references to struct drm_device.pdev")
Reviewed-by: Tian Tao <tiantao6@hisilicon.com>
Reported-by: Tian Tao <tiantao6@hisilicon.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Xinliang Liu <xinliang.liu@linaro.org>
Cc: Tian Tao  <tiantao6@hisilicon.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Cc: Chen Feng <puck.chen@hisilicon.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Gong junjie <gongjunjie2@huawei.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210113113107.12005-1-tzimmermann@suse.de